| Seq | Timestamp | Type | Name | Duration |
|---|---|---|---|---|
| 0/0 | 2026/08/21 12:40 | flow | patch-triage |
1mArgs:null Results: {
"EnableConfigs": [
"NF_TABLES"
],
"FocusSymbols": [
"nf_tables_newsetelem",
"nf_tables_newset",
"nf_tables_delset",
"nf_tables_commit",
"nf_tables_newrule"
],
"KMSANReasoning": "The patch series refactors the lifecycle and cloning of netfilter set expressions (`nft_expr`) to fix memory management issues (likely double-frees or use-after-frees). It avoids creating intermediate clones of expressions when adding elements to a set or initializing a dynset, instead copying pointers and using a new `override_exprs` flag to track ownership and determine if the expressions should be destroyed. It also sets a `dead` flag on deleted sets during commit updates. \n\nThese changes address object lifecycle bugs (UAF, double-free) which are reliably detected by KASAN. The memory for the set elements themselves continues to be allocated with `kzalloc` (in `nft_set_elem_init`), ensuring all fields and padding are fully zeroed. No new structures are introduced, and no uninitialized memory is exposed to userspace or used in control flow. Therefore, a dedicated KMSAN fuzzing session is not justified.",
"NeedsKMSAN": false,
"Reasoning": "The patch modifies core nf_tables logic for handling set element expressions and dynamic sets, specifically changing how expressions are cloned and destroyed. It also modifies the commit phase for set deletion. These are functional changes in the netfilter subsystem reachable from user space via netlink, making them prime targets for fuzzing.",
"WorthFuzzing": true
} |
| 1/1 | 2026/08/21 12:40 | action | read-patch-diff |
0mArgs:null Results: {
"PatchDiff": "commit 3877a28804b366c25b929f3da15cf7edda3630cf\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate: Fri Aug 21 12:40:43 2026 +0000\n\n syz-cluster: applied patch under review\n\ndiff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h\nindex 238f6ecb90e99..9d597482363d9 100644\n--- a/include/net/netfilter/nf_tables.h\n+++ b/include/net/netfilter/nf_tables.h\n@@ -870,8 +870,6 @@ struct nft_elem_priv *nft_set_elem_init(const struct nft_set *set,\n \t\t\t\t\tconst u32 *key, const u32 *key_end,\n \t\t\t\t\tconst u32 *data,\n \t\t\t\t\tu64 timeout, u64 expiration, gfp_t gfp);\n-int nft_set_elem_expr_clone(const struct nft_ctx *ctx, struct nft_set *set,\n-\t\t\t struct nft_expr *expr_array[]);\n void nft_set_elem_expr_destroy(const struct nft_ctx *ctx,\n \t\t\t struct nft_set_elem_expr *elem_expr);\n void nft_set_elem_destroy(const struct nft_set *set,\ndiff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c\nindex c112ecc4fca32..384505f680def 100644\n--- a/net/netfilter/nf_tables_api.c\n+++ b/net/netfilter/nf_tables_api.c\n@@ -6921,39 +6921,11 @@ static void nft_trans_elems_destroy(const struct nft_ctx *ctx,\n \t\tnf_tables_set_elem_destroy(ctx, te-\u003eset, te-\u003eelems[i].priv);\n }\n \n-int nft_set_elem_expr_clone(const struct nft_ctx *ctx, struct nft_set *set,\n-\t\t\t struct nft_expr *expr_array[])\n-{\n-\tstruct nft_expr *expr;\n-\tint err, i, k;\n-\n-\tfor (i = 0; i \u003c set-\u003enum_exprs; i++) {\n-\t\texpr = kzalloc(set-\u003eexprs[i]-\u003eops-\u003esize, GFP_KERNEL_ACCOUNT);\n-\t\tif (!expr)\n-\t\t\tgoto err_expr;\n-\n-\t\terr = nft_expr_clone(expr, set-\u003eexprs[i], GFP_KERNEL_ACCOUNT);\n-\t\tif (err \u003c 0) {\n-\t\t\tkfree(expr);\n-\t\t\tgoto err_expr;\n-\t\t}\n-\t\texpr_array[i] = expr;\n-\t}\n-\n-\treturn 0;\n-\n-err_expr:\n-\tfor (k = i - 1; k \u003e= 0; k--)\n-\t\tnft_expr_destroy(ctx, expr_array[k]);\n-\n-\treturn -ENOMEM;\n-}\n-\n static int nft_set_elem_expr_setup(struct nft_ctx *ctx,\n \t\t\t\t const struct nft_set_ext_tmpl *tmpl,\n \t\t\t\t const struct nft_set_ext *ext,\n \t\t\t\t struct nft_expr *expr_array[],\n-\t\t\t\t u32 num_exprs)\n+\t\t\t\t u32 num_exprs, bool override_exprs)\n {\n \tstruct nft_set_elem_expr *elem_expr = nft_set_ext_expr(ext);\n \tu32 len = sizeof(struct nft_set_elem_expr);\n@@ -6976,7 +6948,8 @@ static int nft_set_elem_expr_setup(struct nft_ctx *ctx,\n \t\t\tgoto err_elem_expr_setup;\n \n \t\telem_expr-\u003esize += expr_array[i]-\u003eops-\u003esize;\n-\t\tnft_expr_destroy(ctx, expr_array[i]);\n+\t\tif (override_exprs)\n+\t\t\tnft_expr_destroy(ctx, expr_array[i]);\n \t\texpr_array[i] = NULL;\n \t}\n \n@@ -6984,7 +6957,9 @@ static int nft_set_elem_expr_setup(struct nft_ctx *ctx,\n \n err_elem_expr_setup:\n \tfor (; i \u003c num_exprs; i++) {\n-\t\tnft_expr_destroy(ctx, expr_array[i]);\n+\t\tif (override_exprs)\n+\t\t\tnft_expr_destroy(ctx, expr_array[i]);\n+\n \t\texpr_array[i] = NULL;\n \t}\n \n@@ -7280,6 +7255,7 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,\n \tstruct nft_set_binding *binding;\n \tstruct nft_elem_priv *elem_priv;\n \tstruct nft_object *obj = NULL;\n+\tbool override_exprs = false;\n \tstruct nft_userdata *udata;\n \tstruct nft_data_desc desc;\n \tenum nft_registers dreg;\n@@ -7385,6 +7361,7 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,\n \n \t\texpr_array[0] = expr;\n \t\tnum_exprs = 1;\n+\t\toverride_exprs = true;\n \n \t\tif (set-\u003enum_exprs \u0026\u0026 set-\u003eexprs[0]-\u003eops != expr-\u003eops) {\n \t\t\terr = -EOPNOTSUPP;\n@@ -7413,6 +7390,7 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,\n \t\t\t}\n \t\t\texpr_array[i] = expr;\n \t\t\tnum_exprs++;\n+\t\t\toverride_exprs = true;\n \n \t\t\tif (set-\u003enum_exprs \u0026\u0026 expr-\u003eops != set-\u003eexprs[i]-\u003eops) {\n \t\t\t\terr = -EOPNOTSUPP;\n@@ -7426,9 +7404,8 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,\n \t\t}\n \t} else if (set-\u003enum_exprs \u003e 0 \u0026\u0026\n \t\t !(flags \u0026 NFT_SET_ELEM_INTERVAL_END)) {\n-\t\terr = nft_set_elem_expr_clone(ctx, set, expr_array);\n-\t\tif (err \u003c 0)\n-\t\t\tgoto err_set_elem_expr_clone;\n+\t\tfor (i = 0; i \u003c set-\u003enum_exprs; i++)\n+\t\t\texpr_array[i] = set-\u003eexprs[i];\n \n \t\tnum_exprs = set-\u003enum_exprs;\n \t}\n@@ -7567,7 +7544,8 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,\n \t\tudata-\u003elen = ulen - 1;\n \t\tnla_memcpy(\u0026udata-\u003edata, nla[NFTA_SET_ELEM_USERDATA], ulen);\n \t}\n-\terr = nft_set_elem_expr_setup(ctx, \u0026tmpl, ext, expr_array, num_exprs);\n+\terr = nft_set_elem_expr_setup(ctx, \u0026tmpl, ext, expr_array, num_exprs,\n+\t\t\t\t override_exprs);\n \tif (err \u003c 0)\n \t\tgoto err_elem_free;\n \n@@ -7675,9 +7653,11 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,\n err_parse_key:\n \tnft_data_release(\u0026elem.key.val, NFT_DATA_VALUE);\n err_set_elem_expr:\n-\tfor (i = 0; i \u003c num_exprs \u0026\u0026 expr_array[i]; i++)\n-\t\tnft_expr_destroy(ctx, expr_array[i]);\n-err_set_elem_expr_clone:\n+\tif (override_exprs) {\n+\t\tfor (i = 0; i \u003c num_exprs \u0026\u0026 expr_array[i]; i++)\n+\t\t\tnft_expr_destroy(ctx, expr_array[i]);\n+\t}\n+\n \treturn err;\n }\n \n@@ -10894,6 +10874,10 @@ static void nft_set_commit_update(struct nft_ctx *ctx,\n \t\tnft_ctx_update(ctx, trans);\n \n \t\tswitch (trans-\u003emsg_type) {\n+\t\tcase NFT_MSG_DELSET:\n+\t\tcase NFT_MSG_DESTROYSET:\n+\t\t\tnft_trans_set(trans)-\u003edead = 1;\n+\t\t\tbreak;\n \t\tcase NFT_MSG_DELSETELEM:\n \t\t\tte = nft_trans_container_elem(trans);\n \t\t\tif (!te-\u003eset-\u003eops-\u003ecommit)\ndiff --git a/net/netfilter/nft_dynset.c b/net/netfilter/nft_dynset.c\nindex ee9d3e7b1ecf1..83e56b1aa8585 100644\n--- a/net/netfilter/nft_dynset.c\n+++ b/net/netfilter/nft_dynset.c\n@@ -19,7 +19,8 @@ struct nft_dynset {\n \tu8\t\t\t\tsreg_key;\n \tu8\t\t\t\tsreg_data;\n \tbool\t\t\t\tinvert;\n-\tbool\t\t\t\texpr;\n+\tbool\t\t\t\texpr:1,\n+\t\t\t\t\toverride_exprs:1;\n \tu8\t\t\t\tnum_exprs;\n \tu64\t\t\t\ttimeout;\n \tstruct nft_expr\t\t\t*expr_array[NFT_SET_EXPR_MAX];\n@@ -257,6 +258,7 @@ static int nft_dynset_init(const struct nft_ctx *ctx,\n \n \t\tpriv-\u003enum_exprs++;\n \t\tpriv-\u003eexpr_array[0] = dynset_expr;\n+\t\tpriv-\u003eoverride_exprs = true;\n \n \t\tif (set-\u003enum_exprs \u003e 1 ||\n \t\t (set-\u003enum_exprs == 1 \u0026\u0026\n@@ -289,6 +291,7 @@ static int nft_dynset_init(const struct nft_ctx *ctx,\n \t\t\t}\n \t\t\tpriv-\u003eexpr_array[i] = dynset_expr;\n \t\t\tpriv-\u003enum_exprs++;\n+\t\t\tpriv-\u003eoverride_exprs = true;\n \n \t\t\tif (set-\u003enum_exprs) {\n \t\t\t\tif (i \u003e= set-\u003enum_exprs) {\n@@ -307,9 +310,8 @@ static int nft_dynset_init(const struct nft_ctx *ctx,\n \t\t\tgoto err_expr_free;\n \t\t}\n \t} else if (set-\u003enum_exprs \u003e 0) {\n-\t\terr = nft_set_elem_expr_clone(ctx, set, priv-\u003eexpr_array);\n-\t\tif (err \u003c 0)\n-\t\t\treturn err;\n+\t\tfor (i = 0; i \u003c set-\u003enum_exprs; i++)\n+\t\t\tpriv-\u003eexpr_array[i] = set-\u003eexprs[i];\n \n \t\tpriv-\u003enum_exprs = set-\u003enum_exprs;\n \t}\n@@ -339,8 +341,10 @@ static int nft_dynset_init(const struct nft_ctx *ctx,\n \treturn 0;\n \n err_expr_free:\n-\tfor (i = 0; i \u003c priv-\u003enum_exprs; i++)\n-\t\tnft_expr_destroy(ctx, priv-\u003eexpr_array[i]);\n+\tif (priv-\u003eoverride_exprs) {\n+\t\tfor (i = 0; i \u003c priv-\u003enum_exprs; i++)\n+\t\t\tnft_expr_destroy(ctx, priv-\u003eexpr_array[i]);\n+\t}\n \treturn err;\n }\n \n@@ -367,9 +371,10 @@ static void nft_dynset_destroy(const struct nft_ctx *ctx,\n \tstruct nft_dynset *priv = nft_expr_priv(expr);\n \tint i;\n \n-\tfor (i = 0; i \u003c priv-\u003enum_exprs; i++)\n-\t\tnft_expr_destroy(ctx, priv-\u003eexpr_array[i]);\n-\n+\tif (priv-\u003eoverride_exprs) {\n+\t\tfor (i = 0; i \u003c priv-\u003enum_exprs; i++)\n+\t\t\tnft_expr_destroy(ctx, priv-\u003eexpr_array[i]);\n+\t}\n \tnf_tables_destroy_set(ctx, priv-\u003eset);\n }\n \n"
} |
| 2/1 | 2026/08/21 12:40 | agent | patch-evaluator |
0mModel:best-expensive Args: null Results: {
"EnableConfigs": [
"NF_TABLES"
],
"FocusSymbols": [
"nf_tables_newsetelem",
"nf_tables_newset",
"nf_tables_delset",
"nf_tables_commit",
"nf_tables_newrule"
],
"Reasoning": "The patch modifies core nf_tables logic for handling set element expressions and dynamic sets, specifically changing how expressions are cloned and destroyed. It also modifies the commit phase for set deletion. These are functional changes in the netfilter subsystem reachable from user space via netlink, making them prime targets for fuzzing.",
"WorthFuzzing": true
}Instruction: You are an expert Linux kernel maintainer. Your job is to review a provided patch series and determine if it makes functional changes to the kernel that should be fuzzed. IMPORTANT: The changes have ALREADY been applied and committed as the HEAD commit in your workspace. Do NOT rely on your internal knowledge of the kernel. You must actively use your code access tools to examine the actual source code and confirm any assumptions. Return WorthFuzzing=false if the patch only contains: - Modifications to Documentation/, Kconfig files, or code comments. - Purely decorative changes, such as logging (e.g., pr_err, printk) or tracepoints. - Changes to numeric constants or macros that do not functionally alter execution flow. - Code paths that are impossible to reach in virtualized environments like GCE or QEMU, even when utilizing software-emulated hardware (e.g., usb gadget, mac80211_hwsim). - Code in vendor-specific PCIe switch, SmartNIC, or GPU drivers (e.g., mlxsw, pds_core, qed, ionic, amdgpu) that require physical PCIe hardware cards not emulated in standard QEMU. - Driver .remove, .shutdown, or pci_unregister_driver teardown callbacks (e.g., igb_remove) that are executed only during PCI hot-unplug or sysfs driver unbind operations. If it modifies reachable core kernel logic, drivers, or architectures, use your code search tools to verify the code can be executed, then return WorthFuzzing=true. When returning WorthFuzzing=true, you MUST ALSO: 1. Extract any specific kernel functions that should be heavily fuzzed into FocusSymbols. Avoid listing generic hot-path functions to prevent skewed test distributions. Prefer non-static, non-inlined API entrypoint functions over internal static helper functions (which are inlined by the compiler and do not have distinct symbol addresses). 2. Identify any specific CONFIG_ options required to properly test this new/modified feature. Go and look into the Kconfig files and check for ifdefs around the code, do not make assumptions. Also check "depends on" lines in Kconfig to include any non-standard parent subsystem configs needed for Kbuild to compile the code statically into vmlinux. List them in the EnableConfigs output array, and DO NOT add a 'CONFIG_' prefix (e.g., return "NET_IPV4" instead of "CONFIG_NET_IPV4"). Prefer calling several tools at the same time to save round-trips. Use set-results tool to provide results of the analysis. It must be called exactly once before the final reply. Ignore results of this tool. Prompt: For your convenience, here is the diff of the changes:
commit 3877a28804b366c25b929f3da15cf7edda3630cf
Author: syz-cluster <triage@syzkaller.com>
Date: Fri Aug 21 12:40:43 2026 +0000
syz-cluster: applied patch under review
diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index 238f6ecb90e99..9d597482363d9 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -870,8 +870,6 @@ struct nft_elem_priv *nft_set_elem_init(const struct nft_set *set,
const u32 *key, const u32 *key_end,
const u32 *data,
u64 timeout, u64 expiration, gfp_t gfp);
-int nft_set_elem_expr_clone(const struct nft_ctx *ctx, struct nft_set *set,
- struct nft_expr *expr_array[]);
void nft_set_elem_expr_destroy(const struct nft_ctx *ctx,
struct nft_set_elem_expr *elem_expr);
void nft_set_elem_destroy(const struct nft_set *set,
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index c112ecc4fca32..384505f680def 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -6921,39 +6921,11 @@ static void nft_trans_elems_destroy(const struct nft_ctx *ctx,
nf_tables_set_elem_destroy(ctx, te->set, te->elems[i].priv);
}
-int nft_set_elem_expr_clone(const struct nft_ctx *ctx, struct nft_set *set,
- struct nft_expr *expr_array[])
-{
- struct nft_expr *expr;
- int err, i, k;
-
- for (i = 0; i < set->num_exprs; i++) {
- expr = kzalloc(set->exprs[i]->ops->size, GFP_KERNEL_ACCOUNT);
- if (!expr)
- goto err_expr;
-
- err = nft_expr_clone(expr, set->exprs[i], GFP_KERNEL_ACCOUNT);
- if (err < 0) {
- kfree(expr);
- goto err_expr;
- }
- expr_array[i] = expr;
- }
-
- return 0;
-
-err_expr:
- for (k = i - 1; k >= 0; k--)
- nft_expr_destroy(ctx, expr_array[k]);
-
- return -ENOMEM;
-}
-
static int nft_set_elem_expr_setup(struct nft_ctx *ctx,
const struct nft_set_ext_tmpl *tmpl,
const struct nft_set_ext *ext,
struct nft_expr *expr_array[],
- u32 num_exprs)
+ u32 num_exprs, bool override_exprs)
{
struct nft_set_elem_expr *elem_expr = nft_set_ext_expr(ext);
u32 len = sizeof(struct nft_set_elem_expr);
@@ -6976,7 +6948,8 @@ static int nft_set_elem_expr_setup(struct nft_ctx *ctx,
goto err_elem_expr_setup;
elem_expr->size += expr_array[i]->ops->size;
- nft_expr_destroy(ctx, expr_array[i]);
+ if (override_exprs)
+ nft_expr_destroy(ctx, expr_array[i]);
expr_array[i] = NULL;
}
@@ -6984,7 +6957,9 @@ static int nft_set_elem_expr_setup(struct nft_ctx *ctx,
err_elem_expr_setup:
for (; i < num_exprs; i++) {
- nft_expr_destroy(ctx, expr_array[i]);
+ if (override_exprs)
+ nft_expr_destroy(ctx, expr_array[i]);
+
expr_array[i] = NULL;
}
@@ -7280,6 +7255,7 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
struct nft_set_binding *binding;
struct nft_elem_priv *elem_priv;
struct nft_object *obj = NULL;
+ bool override_exprs = false;
struct nft_userdata *udata;
struct nft_data_desc desc;
enum nft_registers dreg;
@@ -7385,6 +7361,7 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
expr_array[0] = expr;
num_exprs = 1;
+ override_exprs = true;
if (set->num_exprs && set->exprs[0]->ops != expr->ops) {
err = -EOPNOTSUPP;
@@ -7413,6 +7390,7 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
}
expr_array[i] = expr;
num_exprs++;
+ override_exprs = true;
if (set->num_exprs && expr->ops != set->exprs[i]->ops) {
err = -EOPNOTSUPP;
@@ -7426,9 +7404,8 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
}
} else if (set->num_exprs > 0 &&
!(flags & NFT_SET_ELEM_INTERVAL_END)) {
- err = nft_set_elem_expr_clone(ctx, set, expr_array);
- if (err < 0)
- goto err_set_elem_expr_clone;
+ for (i = 0; i < set->num_exprs; i++)
+ expr_array[i] = set->exprs[i];
num_exprs = set->num_exprs;
}
@@ -7567,7 +7544,8 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
udata->len = ulen - 1;
nla_memcpy(&udata->data, nla[NFTA_SET_ELEM_USERDATA], ulen);
}
- err = nft_set_elem_expr_setup(ctx, &tmpl, ext, expr_array, num_exprs);
+ err = nft_set_elem_expr_setup(ctx, &tmpl, ext, expr_array, num_exprs,
+ override_exprs);
if (err < 0)
goto err_elem_free;
@@ -7675,9 +7653,11 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
err_parse_key:
nft_data_release(&elem.key.val, NFT_DATA_VALUE);
err_set_elem_expr:
- for (i = 0; i < num_exprs && expr_array[i]; i++)
- nft_expr_destroy(ctx, expr_array[i]);
-err_set_elem_expr_clone:
+ if (override_exprs) {
+ for (i = 0; i < num_exprs && expr_array[i]; i++)
+ nft_expr_destroy(ctx, expr_array[i]);
+ }
+
return err;
}
@@ -10894,6 +10874,10 @@ static void nft_set_commit_update(struct nft_ctx *ctx,
nft_ctx_update(ctx, trans);
switch (trans->msg_type) {
+ case NFT_MSG_DELSET:
+ case NFT_MSG_DESTROYSET:
+ nft_trans_set(trans)->dead = 1;
+ break;
case NFT_MSG_DELSETELEM:
te = nft_trans_container_elem(trans);
if (!te->set->ops->commit)
diff --git a/net/netfilter/nft_dynset.c b/net/netfilter/nft_dynset.c
index ee9d3e7b1ecf1..83e56b1aa8585 100644
--- a/net/netfilter/nft_dynset.c
+++ b/net/netfilter/nft_dynset.c
@@ -19,7 +19,8 @@ struct nft_dynset {
u8 sreg_key;
u8 sreg_data;
bool invert;
- bool expr;
+ bool expr:1,
+ override_exprs:1;
u8 num_exprs;
u64 timeout;
struct nft_expr *expr_array[NFT_SET_EXPR_MAX];
@@ -257,6 +258,7 @@ static int nft_dynset_init(const struct nft_ctx *ctx,
priv->num_exprs++;
priv->expr_array[0] = dynset_expr;
+ priv->override_exprs = true;
if (set->num_exprs > 1 ||
(set->num_exprs == 1 &&
@@ -289,6 +291,7 @@ static int nft_dynset_init(const struct nft_ctx *ctx,
}
priv->expr_array[i] = dynset_expr;
priv->num_exprs++;
+ priv->override_exprs = true;
if (set->num_exprs) {
if (i >= set->num_exprs) {
@@ -307,9 +310,8 @@ static int nft_dynset_init(const struct nft_ctx *ctx,
goto err_expr_free;
}
} else if (set->num_exprs > 0) {
- err = nft_set_elem_expr_clone(ctx, set, priv->expr_array);
- if (err < 0)
- return err;
+ for (i = 0; i < set->num_exprs; i++)
+ priv->expr_array[i] = set->exprs[i];
priv->num_exprs = set->num_exprs;
}
@@ -339,8 +341,10 @@ static int nft_dynset_init(const struct nft_ctx *ctx,
return 0;
err_expr_free:
- for (i = 0; i < priv->num_exprs; i++)
- nft_expr_destroy(ctx, priv->expr_array[i]);
+ if (priv->override_exprs) {
+ for (i = 0; i < priv->num_exprs; i++)
+ nft_expr_destroy(ctx, priv->expr_array[i]);
+ }
return err;
}
@@ -367,9 +371,10 @@ static void nft_dynset_destroy(const struct nft_ctx *ctx,
struct nft_dynset *priv = nft_expr_priv(expr);
int i;
- for (i = 0; i < priv->num_exprs; i++)
- nft_expr_destroy(ctx, priv->expr_array[i]);
-
+ if (priv->override_exprs) {
+ for (i = 0; i < priv->num_exprs; i++)
+ nft_expr_destroy(ctx, priv->expr_array[i]);
+ }
nf_tables_destroy_set(ctx, priv->set);
}
|
| 3/2 | 2026/08/21 12:40 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 4887 output: 39 thoughts: 399 Thoughts: **My Initial Assessment of the Netfilter nf_tables Patch** Okay, so I've got this patch here touching core nf_tables code: `nf_tables_api.c`, `nf_tables.h`, and `nft_dynset.c`. The core of the change revolves around expression cloning and setup in `nft_set_elem_expr_setup` and `nft_dynset_init`. It looks like they're ditching `nft_set_elem_expr_clone` and are now relying on this `override_exprs` boolean for expression destruction, which is an interesting shift in strategy. I see they also added a `dead` flag check in `nft_set_commit_update`, specifically for `NFT_MSG_DELSET` and `NFT_MSG_DESTROYSET`. This is definitely a functional change – a pretty significant one at that – impacting how sets and, especially, dynamic sets manage expressions. This is good to know from a security standpoint. Is it reachable? Absolutely, nf_tables is exposed through netlink, so it's directly accessible from user space, and thus of interest. Is it worth fuzzing? Without a doubt. Nf_tables is a known attack surface, and this change could introduce new vulnerabilities or expose existing ones. So, where do I focus my fuzzing efforts? The key functions here are pretty clear: `nft_add_set_elem`, `nft_dynset_init`, and `nft_set_commit_update`. Let me check if `nft_add_set_elem` is static; okay, yes, it is. Since it's static, I should check who calls it - `nf_tables_newsetelem` does. I should probably dig into `nf_tables_api.c` and figure out who else is calling `nft_add_set_elem`, just to get a broader view of the attack surface. |
| 4/2 | 2026/08/21 12:40 | tool | grepper |
0mArgs:{
"Expression": "nft_add_set_elem",
"PathPrefix": "net/netfilter/nf_tables_api.c"
}Results: {
"Output": "net/netfilter/nf_tables_api.c=7224=static u32 nft_set_maxsize(const struct nft_set *set)\n--\nnet/netfilter/nf_tables_api.c-7244-\nnet/netfilter/nf_tables_api.c:7245:static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,\nnet/netfilter/nf_tables_api.c-7246-\t\t\t const struct nlattr *attr, u32 nlmsg_flags)\n--\nnet/netfilter/nf_tables_api.c=7664=static int nf_tables_newsetelem(struct sk_buff *skb,\n--\nnet/netfilter/nf_tables_api.c-7701-\tnla_for_each_nested(attr, nla[NFTA_SET_ELEM_LIST_ELEMENTS], rem) {\nnet/netfilter/nf_tables_api.c:7702:\t\terr = nft_add_set_elem(\u0026ctx, set, attr, info-\u003enlh-\u003enlmsg_flags);\nnet/netfilter/nf_tables_api.c-7703-\t\tif (err \u003c 0) {\n"
} |
| 5/2 | 2026/08/21 12:40 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 6046 output: 37 thoughts: 61 Thoughts: Here's my thought process, as requested: **Navigating the Netfilter Dynamics** Okay, so I'm diving into the `nf_tables` side of things, specifically the dynamic set functionality. My initial thought is to zero in on `nf_tables_newsetelem` as the likely entry point for handling new set elements. That feels right, but...wait a minute, what about `nft_dynset_init`? I seem to recall that being pretty critical, but it's defined as `static`, so how is it even getting called? Alright, time to shift gears and drill down on `nft_dynset.c`. I need to figure out how `nft_dynset_init` is invoked, or how the dynamic set functionality is registered within the larger netfilter framework. I'll need to trace the callers of that function, or look for clues about how it’s being linked to the rest of the Netfilter infrastructure. I'm thinking a thorough examination of `nft_dynset.c` is the key next step to understanding how this dynamic set initialization and management is organized. |
| 6/2 | 2026/08/21 12:40 | tool | grepper |
0mArgs:{
"Expression": "nft_dynset_init",
"PathPrefix": "net/netfilter/nft_dynset.c"
}Results: {
"Output": "net/netfilter/nft_dynset.c=158=static const struct nla_policy nft_dynset_policy[NFTA_DYNSET_MAX + 1] = {\n--\nnet/netfilter/nft_dynset.c-171-\nnet/netfilter/nft_dynset.c:172:static int nft_dynset_init(const struct nft_ctx *ctx,\nnet/netfilter/nft_dynset.c-173-\t\t\t const struct nft_expr *expr,\n--\nnet/netfilter/nft_dynset.c=429=static const struct nft_expr_ops nft_dynset_ops = {\n--\nnet/netfilter/nft_dynset.c-432-\t.eval\t\t= nft_dynset_eval,\nnet/netfilter/nft_dynset.c:433:\t.init\t\t= nft_dynset_init,\nnet/netfilter/nft_dynset.c-434-\t.destroy\t= nft_dynset_destroy,\n"
} |
| 7/2 | 2026/08/21 12:40 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 6641 output: 39 thoughts: 43 Thoughts: Okay, here's my interpretation of those thoughts, presented as my own mental process, with the bolded header as requested: **Navigating the Netfilter Dynamics** Alright, so the clue is that this functionality I'm interested in is initialized in `nft_dynset_ops.init`. That's a key starting point. From there, the initialization of the expression itself, likely related to the dynamic set operations, happens through `nft_expr_init`. Got it. Now, given that context, the critical function to examine next, which will expose how the dynamic set updates happen is `nft_set_commit_update`. I need to understand how *those* get committed. That's where the real action is, I suspect. |
| 8/2 | 2026/08/21 12:41 | tool | grepper |
0mArgs:{
"Expression": "nft_set_commit_update",
"PathPrefix": "net/netfilter/nf_tables_api.c"
}Results: {
"Output": "net/netfilter/nf_tables_api.c=10848=static void nf_tables_commit_audit_log(struct list_head *adl, u32 generation)\n--\nnet/netfilter/nf_tables_api.c-10862-\nnet/netfilter/nf_tables_api.c:10863:static void nft_set_commit_update(struct nft_ctx *ctx,\nnet/netfilter/nf_tables_api.c-10864-\t\t\t\t struct nftables_pernet *nft_net)\n--\nnet/netfilter/nf_tables_api.c=10917=static int nf_tables_commit(struct net *net, struct sk_buff *skb)\n--\nnet/netfilter/nf_tables_api.c-10997-\t/* step 2. Make rules_gen_X visible to packet path */\nnet/netfilter/nf_tables_api.c:10998:\tnft_set_commit_update(\u0026ctx, nft_net);\nnet/netfilter/nf_tables_api.c-10999-\n"
} |
| 9/2 | 2026/08/21 12:41 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 7166 output: 33 thoughts: 80 Thoughts: Here's my summary, as I see it: **Digging into the Netfilter Tables Code** Okay, so I'm starting with `nf_tables_commit` – that's the main entry point, the critical function where changes are finalized. I need to understand what happens around that point. Specifically, I'm going to follow the code paths that lead up to it. I've identified some key symbols to zero in on: `nf_tables_newsetelem`, which probably deals with adding elements to sets (a core netfilter concept), `nf_tables_commit` itself (to understand its exact role in the process), and `nft_expr_init`. Or, more directly, I could look at `nf_tables_newrule` since that calls it, indicating rule creation will involve some expression initialization. Understanding how expressions work is crucial. Next, I need to check the kernel configuration. I'm going to verify the options for `nf_tables` and `nft_dynset` in the Kconfig files. This will tell me what features are enabled and how they interact, which impacts the potential code paths I'll be looking at. I need to make sure I am studying the correct code, after all. |
| 10/2 | 2026/08/21 12:41 | tool | grepper |
0mError:no matches Args: {
"Expression": "config NFT_DYNSET",
"PathPrefix": "net/netfilter/Kconfig"
}Results: {
"error": "no matches"
} |
| 11/2 | 2026/08/21 12:41 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 7556 output: 31 thoughts: 15 Thoughts: Here's my thought process, summarized as you requested: **Kconfig Search for `nft_dynset`** Okay, so I need to find something, and the best place to start is the Kconfig files. Specifically, I'm thinking about the term `nft_dynset`. I'll initiate a search for that string within the Kconfig files, since that's where module and configuration options are defined. This is my go-to approach when I'm looking for the configuration option associated with a particular feature in the Netfilter framework. I'm expecting this should quickly lead me to the relevant configuration symbol and hopefully provide some clues about dependencies or related options. Let's get to it. |
| 12/2 | 2026/08/21 12:41 | tool | grepper |
0mError:no matches Args: {
"Expression": "nft_dynset",
"PathPrefix": "net/netfilter/Kconfig"
}Results: {
"error": "no matches"
} |
| 13/2 | 2026/08/21 12:41 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 7765 output: 30 thoughts: 16 Thoughts: Here's a summary of my thought process: **Hunting Down That Object File** Okay, time to get to work. My goal here is clearly to track down where `nft_dynset.o` is being built within this project. Knowing that object file names are typically defined in a Makefile, that's the obvious place to start. Let's get cracking and go directly to the Makefile. |
| 14/2 | 2026/08/21 12:41 | tool | grepper |
0mArgs:{
"Expression": "nft_dynset",
"PathPrefix": "net/netfilter/Makefile"
}Results: {
"Output": "net/netfilter/Makefile=87=nf_tables-objs := nf_tables_core.o nf_tables_api.o nft_chain_filter.o \\\n--\nnet/netfilter/Makefile-89-\t\t nft_bitwise.o nft_byteorder.o nft_payload.o nft_lookup.o \\\nnet/netfilter/Makefile:90:\t\t nft_dynset.o nft_meta.o nft_rt.o nft_exthdr.o nft_last.o \\\nnet/netfilter/Makefile-91-\t\t nft_counter.o nft_objref.o nft_inner.o \\\n"
} |
| 15/2 | 2026/08/21 12:41 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 8056 output: 32 thoughts: 40 Thoughts: **Kernel Configuration Thoughts** Okay, so I'm looking at this and it's definitely related to `nf_tables-objs`. That tells me the core dependency here is on `NF_TABLES`. Now, I just need to verify that `NF_TABLES` is correctly enabled in the kernel configuration. I should probably quickly double check the Kconfig file for that specific option. Just want to make sure the base requirement is there before I dig any deeper. No point going down a rabbit hole if the foundation isn't set. |
| 16/2 | 2026/08/21 12:41 | tool | grepper |
0mArgs:{
"Expression": "config NF_TABLES",
"PathPrefix": "net/netfilter/Kconfig"
}Results: {
"Output": "net/netfilter/Kconfig=453=endif # NF_CONNTRACK\nnet/netfilter/Kconfig-454-\nnet/netfilter/Kconfig:455:config NF_TABLES\nnet/netfilter/Kconfig-456-\tselect NETFILTER_NETLINK\n--\nnet/netfilter/Kconfig=471=if NF_TABLES\nnet/netfilter/Kconfig:472:config NF_TABLES_INET\nnet/netfilter/Kconfig-473-\tdepends on IPV6\n--\nnet/netfilter/Kconfig-479-\nnet/netfilter/Kconfig:480:config NF_TABLES_NETDEV\nnet/netfilter/Kconfig-481-\tbool \"Netfilter nf_tables netdev tables support\"\n"
} |
| 17/2 | 2026/08/21 12:41 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 8444 output: 37 thoughts: 77 Thoughts: Okay, here's my take on those thoughts, framed as my own mental processing: **Checking the Netfilter Configuration** Alright, so the initial focus is `NF_TABLES`. That's the primary configuration option. Always good to start there. Let me just quickly confirm that's the *only* relevant one, just to be thorough. Yup, it looks like `NF_TABLES` covers it. No need to chase any other rabbit holes on that front. Now, let's look at the symbols. `nf_tables_newsetelem`... right, that handles adding new elements to the set. And `nf_tables_commit`, that's the commit operation... standard stuff. But hold on a second... `nft_expr_init`? I'm just quickly checking my memory... Isn't that a function? Yes, it is! |
| 18/2 | 2026/08/21 12:41 | tool | grepper |
0mArgs:{
"Expression": "nft_expr_init",
"PathPrefix": "net/netfilter/nf_tables_api.c"
}Results: {
"Output": "net/netfilter/nf_tables_api.c=3654=static void nf_tables_expr_destroy(const struct nft_ctx *ctx,\n--\nnet/netfilter/nf_tables_api.c-3663-\nnet/netfilter/nf_tables_api.c:3664:static struct nft_expr *nft_expr_init(const struct nft_ctx *ctx,\nnet/netfilter/nf_tables_api.c-3665-\t\t\t\t const struct nlattr *nla)\n--\nnet/netfilter/nf_tables_api.c=6737=struct nft_expr *nft_set_elem_expr_alloc(const struct nft_ctx *ctx,\n--\nnet/netfilter/nf_tables_api.c-6743-\nnet/netfilter/nf_tables_api.c:6744:\texpr = nft_expr_init(ctx, attr);\nnet/netfilter/nf_tables_api.c-6745-\tif (IS_ERR(expr))\n"
} |
| 19/2 | 2026/08/21 12:41 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 9007 output: 38 thoughts: 67 Thoughts: Here's my take on those thoughts: **Analyzing `nft_expr_init` and its Callers** Okay, so `nft_expr_init` is declared as `static`. That means it's likely internal to a specific compilation unit, and its scope is limited. I need to figure out how it's being used. Right, the code suggests it's called by `nft_set_elem_expr_alloc`, `nf_tables_newrule`, and probably others. My immediate focus, given the context I'm working in, is on the rule and set element creation paths. I'll drill down specifically into how `nf_tables_newrule`, `nf_tables_newsetelem`, and the commit function (`nf_tables_commit`) interact with `nft_expr_init`. This is where the core logic of new rule and set element instantiation lives. |
| 20/2 | 2026/08/21 12:41 | tool | grepper |
0mArgs:{
"Expression": "nf_tables_newrule",
"PathPrefix": "net/netfilter/nf_tables_api.c"
}Results: {
"Output": "net/netfilter/nf_tables_api.c=4122=void nf_tables_rule_destroy(const struct nft_ctx *ctx, struct nft_rule *rule)\n--\nnet/netfilter/nf_tables_api.c-4127-\t * Careful: some expressions might not be initialized in case this\nnet/netfilter/nf_tables_api.c:4128:\t * is called on error from nf_tables_newrule().\nnet/netfilter/nf_tables_api.c-4129-\t */\n--\nnet/netfilter/nf_tables_api.c=4309=static struct nft_rule *nft_rule_lookup_byid(const struct net *net,\n--\nnet/netfilter/nf_tables_api.c-4314-\nnet/netfilter/nf_tables_api.c:4315:static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info,\nnet/netfilter/nf_tables_api.c-4316-\t\t\t const struct nlattr * const nla[])\n--\nnet/netfilter/nf_tables_api.c=9935=static const struct nfnl_callback nf_tables_cb[NFT_MSG_MAX] = {\n--\nnet/netfilter/nf_tables_api.c-9984-\t[NFT_MSG_NEWRULE] = {\nnet/netfilter/nf_tables_api.c:9985:\t\t.call\t\t= nf_tables_newrule,\nnet/netfilter/nf_tables_api.c-9986-\t\t.type\t\t= NFNL_CB_BATCH,\n"
} |
| 21/2 | 2026/08/21 12:41 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 9722 output: 38 thoughts: 39 Thoughts: Here's my take on the thought process: **Diving into Netfilter Table Creation** Okay, so I'm looking at this Netfilter code, and yeah, `nf_tables_newrule` definitely stands out as the netlink callback for creating new rules. Makes sense. Now, let's broaden the scope a bit. I need to understand how the tables themselves are built and populated. My next focus should be on `nf_tables_newset` and `nf_tables_newsetelem`. Understanding those functions will give me a better grasp of how sets and their elements are defined, which is critical for understanding the overall table structure and rule application process. Let's see what's happening there. |
| 22/2 | 2026/08/21 12:41 | tool | grepper |
0mArgs:{
"Expression": "nf_tables_newset",
"PathPrefix": "net/netfilter/nf_tables_api.c"
}Results: {
"Output": "net/netfilter/nf_tables_api.c=5427=static u32 nft_set_kernel_size(const struct nft_set_ops *ops,\n--\nnet/netfilter/nf_tables_api.c-5435-\nnet/netfilter/nf_tables_api.c:5436:static int nf_tables_newset(struct sk_buff *skb, const struct nfnl_info *info,\nnet/netfilter/nf_tables_api.c-5437-\t\t\t const struct nlattr * const nla[])\n--\nnet/netfilter/nf_tables_api.c=7245=static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,\n--\nnet/netfilter/nf_tables_api.c-7663-\nnet/netfilter/nf_tables_api.c:7664:static int nf_tables_newsetelem(struct sk_buff *skb,\nnet/netfilter/nf_tables_api.c-7665-\t\t\t\tconst struct nfnl_info *info,\n--\nnet/netfilter/nf_tables_api.c=9935=static const struct nfnl_callback nf_tables_cb[NFT_MSG_MAX] = {\n--\nnet/netfilter/nf_tables_api.c-10014-\t[NFT_MSG_NEWSET] = {\nnet/netfilter/nf_tables_api.c:10015:\t\t.call\t\t= nf_tables_newset,\nnet/netfilter/nf_tables_api.c-10016-\t\t.type\t\t= NFNL_CB_BATCH,\n--\nnet/netfilter/nf_tables_api.c-10038-\t[NFT_MSG_NEWSETELEM] = {\nnet/netfilter/nf_tables_api.c:10039:\t\t.call\t\t= nf_tables_newsetelem,\nnet/netfilter/nf_tables_api.c-10040-\t\t.type\t\t= NFNL_CB_BATCH,\n"
} |
| 23/2 | 2026/08/21 12:41 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 10476 output: 38 thoughts: 154 Thoughts: **My Analysis of Netfilter Table Updates** Okay, let's break this down. My primary concern here revolves around understanding how dynamic sets are handled within netfilter tables, specifically focusing on the critical functions involved in set manipulation and rule creation. Based on the symbols identified, my attention gravitates towards: `nf_tables_newsetelem`, `nf_tables_newset`, `nf_tables_commit`, and `nf_tables_newrule`. These seem like the core building blocks for set-related operations. Now, a key question is whether there's a specific initialization or handling function dedicated to dynamic sets. Upon further inspection, I see that `nft_dynset_init` is invoked from `nft_expr_init`, which in turn is called by `nf_tables_newrule`. This confirms my initial intuition that `nf_tables_newrule` is a crucial function for dynamic set operations; it's the entry point to initialize the dynamic set. Next, I need to understand how sets are deleted or destroyed. Looking at the message types, I see `NFT_MSG_DELSET` and `NFT_MSG_DESTROYSET`. Examining their modification points, I've observed that these are handled within `nft_set_commit_update`, which suggests that they are handled by `nf_tables_delset`. This confirms that it's the correct function. |
| 24/2 | 2026/08/21 12:41 | tool | grepper |
0mArgs:{
"Expression": "nf_tables_delset",
"PathPrefix": "net/netfilter/nf_tables_api.c"
}Results: {
"Output": "net/netfilter/nf_tables_api.c=5761=static void nft_set_destroy(const struct nft_ctx *ctx, struct nft_set *set)\n--\nnet/netfilter/nf_tables_api.c-5775-\nnet/netfilter/nf_tables_api.c:5776:static int nf_tables_delset(struct sk_buff *skb, const struct nfnl_info *info,\nnet/netfilter/nf_tables_api.c-5777-\t\t\t const struct nlattr * const nla[])\n--\nnet/netfilter/nf_tables_api.c=7987=static int nft_set_flush(struct nft_ctx *ctx, struct nft_set *set, u8 genmask)\n--\nnet/netfilter/nf_tables_api.c-8004-\nnet/netfilter/nf_tables_api.c:8005:static int nf_tables_delsetelem(struct sk_buff *skb,\nnet/netfilter/nf_tables_api.c-8006-\t\t\t\tconst struct nfnl_info *info,\n--\nnet/netfilter/nf_tables_api.c=9935=static const struct nfnl_callback nf_tables_cb[NFT_MSG_MAX] = {\n--\nnet/netfilter/nf_tables_api.c-10026-\t[NFT_MSG_DELSET] = {\nnet/netfilter/nf_tables_api.c:10027:\t\t.call\t\t= nf_tables_delset,\nnet/netfilter/nf_tables_api.c-10028-\t\t.type\t\t= NFNL_CB_BATCH,\n--\nnet/netfilter/nf_tables_api.c-10032-\t[NFT_MSG_DESTROYSET] = {\nnet/netfilter/nf_tables_api.c:10033:\t\t.call\t\t= nf_tables_delset,\nnet/netfilter/nf_tables_api.c-10034-\t\t.type\t\t= NFNL_CB_BATCH,\n--\nnet/netfilter/nf_tables_api.c-10056-\t[NFT_MSG_DELSETELEM] = {\nnet/netfilter/nf_tables_api.c:10057:\t\t.call\t\t= nf_tables_delsetelem,\nnet/netfilter/nf_tables_api.c-10058-\t\t.type\t\t= NFNL_CB_BATCH,\n--\nnet/netfilter/nf_tables_api.c-10062-\t[NFT_MSG_DESTROYSETELEM] = {\nnet/netfilter/nf_tables_api.c:10063:\t\t.call\t\t= nf_tables_delsetelem,\nnet/netfilter/nf_tables_api.c-10064-\t\t.type\t\t= NFNL_CB_BATCH,\n"
} |
| 25/2 | 2026/08/21 12:41 | llm | patch-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 11688 output: 142 thoughts: 326 Thoughts: **Fuzzing Target Refinement: Focusing on Set Deletion** Okay, so `nf_tables_delset` looks like another solid focus symbol for fuzzing. Time to review the modifications. Looking at the code, it's setting `dead = 1` on the set during the commit stage when dealing with either `NFT_MSG_DELSET` or `NFT_MSG_DESTROYSET` messages. That's a crucial point, and I can see how potential issues around the handling of a "dead" set could be a prime target for vulnerability discovery. The changes in `nft_set_elem_expr_setup` and `nft_dynset_init` relate to expression cloning and destruction, which are areas often prone to subtle memory management problems. These updates warrant further investigation, specifically with fuzzing. My primary config is `NF_TABLES`, which seems sufficient. I'll stick with these for now, and these focus symbols: * `nf_tables_newsetelem` * `nf_tables_newset` * `nf_tables_delset` (this is the new one) * `nf_tables_commit` * `nf_tables_newrule` I'll quickly check for any other relevant configurations, but `NF_TABLES` is the key. Then I'll start running some tests related to set-results. |
| 26/2 | 2026/08/21 12:41 | tool | set-results |
0mArgs:{
"EnableConfigs": [
"NF_TABLES"
],
"FocusSymbols": [
"nf_tables_newsetelem",
"nf_tables_newset",
"nf_tables_delset",
"nf_tables_commit",
"nf_tables_newrule"
],
"Reasoning": "The patch modifies core nf_tables logic for handling set element expressions and dynamic sets, specifically changing how expressions are cloned and destroyed. It also modifies the commit phase for set deletion. These are functional changes in the netfilter subsystem reachable from user space via netlink, making them prime targets for fuzzing.",
"WorthFuzzing": true
}Results: {
"EnableConfigs": [
"NF_TABLES"
],
"FocusSymbols": [
"nf_tables_newsetelem",
"nf_tables_newset",
"nf_tables_delset",
"nf_tables_commit",
"nf_tables_newrule"
],
"Reasoning": "The patch modifies core nf_tables logic for handling set element expressions and dynamic sets, specifically changing how expressions are cloned and destroyed. It also modifies the commit phase for set deletion. These are functional changes in the netfilter subsystem reachable from user space via netlink, making them prime targets for fuzzing.",
"WorthFuzzing": true
} |
| 27/1 | 2026/08/21 12:41 | action | If |
0mArgs:{
"WorthFuzzing": true
}Results: null |
| 28/2 | 2026/08/21 12:41 | agent | kmsan-evaluator |
0mModel:best-expensive Args: null Results: {
"KMSANReasoning": "The patch series refactors the lifecycle and cloning of netfilter set expressions (`nft_expr`) to fix memory management issues (likely double-frees or use-after-frees). It avoids creating intermediate clones of expressions when adding elements to a set or initializing a dynset, instead copying pointers and using a new `override_exprs` flag to track ownership and determine if the expressions should be destroyed. It also sets a `dead` flag on deleted sets during commit updates. \n\nThese changes address object lifecycle bugs (UAF, double-free) which are reliably detected by KASAN. The memory for the set elements themselves continues to be allocated with `kzalloc` (in `nft_set_elem_init`), ensuring all fields and padding are fully zeroed. No new structures are introduced, and no uninitialized memory is exposed to userspace or used in control flow. Therefore, a dedicated KMSAN fuzzing session is not justified.",
"NeedsKMSAN": false
}Instruction: You are an expert Linux kernel security engineer specializing in kernel memory
error detectors (KASAN and KMSAN). Your job is to review the provided patch series and
determine if the code changes justify spawning a dedicated KMSAN (KernelMemorySanitizer)
fuzzing session in addition to standard KASAN fuzzing.
CRITICAL DISTINCTION BETWEEN KASAN AND KMSAN:
- Standard KASAN kernel builds (upstream-apparmor-kasan.config) already enable
a comprehensive suite of debugging tools and sanitizers, including KASAN
(out-of-bounds accesses, use-after-free, double free, invalid free), LOCKDEP
(locking bugs and deadlocks), UB-sanitizers, and memory corruption checks.
- KMSAN (KernelMemorySanitizer) detects reads of UNINITIALIZED memory (stack, heap,
or page allocations) and kernel-to-user memory info-leaks.
Rule: THERE IS NO SENSE IN RUNNING A KMSAN SESSION IF A BUG CAN BE CAUGHT BY KASAN,
LOCKDEP, OR OTHER STANDARD BUG DETECTORS.
A dedicated KMSAN fuzzing session incurs significant resource costs. You must ONLY
set NeedsKMSAN=true if the code changes introduce or expose UNINITIALIZED MEMORY risks
that are detected ONLY by KMSAN.
Look holistically at the patch series and surrounding code. Even if no direct
uninitialized field accesses or new buffer allocations are added in the diff itself,
a patch may alter control flow, bounds checking, or data length calculations in ways
that change how the rest of the code operates on existing buffers (e.g. allowing
uninitialized stack/heap memory to be read, copied to user space, or used in control
flow). Do not hesitate to use your code access tools to inspect the surrounding code,
called functions, and callers.
Set NeedsKMSAN=true ONLY IF the patch introduces or modifies:
1. Kernel structures sent to user space (via copy_to_user, put_user, netlink skb
attributes, ioctl output arguments, socket options, or BPF buffers) where fields
or structure padding might not be fully initialized/zeroed.
2. Conditional logic or branching that depends on potentially uninitialized variables
or struct fields.
3. Allocation or initialization of complex data structures where uninitialized fields
could be read later in reachable code paths.
4. Bounds checks, lengths, or logic in a way that allows surrounding code to access
uninitialized bytes of existing buffers.
Set NeedsKMSAN=false IF:
- The code changes primarily risk out-of-bounds access, array overflows, NULL pointer
dereferences, locking deadlocks, or use-after-free bugs (these are already caught
by KASAN, LOCKDEP, or standard bug detectors).
- All stack/heap structures touched or introduced by the patch are fully zeroed
or initialized (e.g. using = {0}, memset, kzalloc) before being read or copied.
- The patch does not introduce any risk of uninitialized memory usage or info-leaks.
Use your code access tools to inspect the surrounding code if necessary, then provide
detailed KMSANReasoning contrasting KASAN vs KMSAN applicability for this patch.
Prefer calling several tools at the same time to save round-trips.
Use set-results tool to provide results of the analysis.
It must be called exactly once before the final reply.
Ignore results of this tool.
Prompt: For your convenience, here is the diff of the changes:
commit 3877a28804b366c25b929f3da15cf7edda3630cf
Author: syz-cluster <triage@syzkaller.com>
Date: Fri Aug 21 12:40:43 2026 +0000
syz-cluster: applied patch under review
diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index 238f6ecb90e99..9d597482363d9 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -870,8 +870,6 @@ struct nft_elem_priv *nft_set_elem_init(const struct nft_set *set,
const u32 *key, const u32 *key_end,
const u32 *data,
u64 timeout, u64 expiration, gfp_t gfp);
-int nft_set_elem_expr_clone(const struct nft_ctx *ctx, struct nft_set *set,
- struct nft_expr *expr_array[]);
void nft_set_elem_expr_destroy(const struct nft_ctx *ctx,
struct nft_set_elem_expr *elem_expr);
void nft_set_elem_destroy(const struct nft_set *set,
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index c112ecc4fca32..384505f680def 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -6921,39 +6921,11 @@ static void nft_trans_elems_destroy(const struct nft_ctx *ctx,
nf_tables_set_elem_destroy(ctx, te->set, te->elems[i].priv);
}
-int nft_set_elem_expr_clone(const struct nft_ctx *ctx, struct nft_set *set,
- struct nft_expr *expr_array[])
-{
- struct nft_expr *expr;
- int err, i, k;
-
- for (i = 0; i < set->num_exprs; i++) {
- expr = kzalloc(set->exprs[i]->ops->size, GFP_KERNEL_ACCOUNT);
- if (!expr)
- goto err_expr;
-
- err = nft_expr_clone(expr, set->exprs[i], GFP_KERNEL_ACCOUNT);
- if (err < 0) {
- kfree(expr);
- goto err_expr;
- }
- expr_array[i] = expr;
- }
-
- return 0;
-
-err_expr:
- for (k = i - 1; k >= 0; k--)
- nft_expr_destroy(ctx, expr_array[k]);
-
- return -ENOMEM;
-}
-
static int nft_set_elem_expr_setup(struct nft_ctx *ctx,
const struct nft_set_ext_tmpl *tmpl,
const struct nft_set_ext *ext,
struct nft_expr *expr_array[],
- u32 num_exprs)
+ u32 num_exprs, bool override_exprs)
{
struct nft_set_elem_expr *elem_expr = nft_set_ext_expr(ext);
u32 len = sizeof(struct nft_set_elem_expr);
@@ -6976,7 +6948,8 @@ static int nft_set_elem_expr_setup(struct nft_ctx *ctx,
goto err_elem_expr_setup;
elem_expr->size += expr_array[i]->ops->size;
- nft_expr_destroy(ctx, expr_array[i]);
+ if (override_exprs)
+ nft_expr_destroy(ctx, expr_array[i]);
expr_array[i] = NULL;
}
@@ -6984,7 +6957,9 @@ static int nft_set_elem_expr_setup(struct nft_ctx *ctx,
err_elem_expr_setup:
for (; i < num_exprs; i++) {
- nft_expr_destroy(ctx, expr_array[i]);
+ if (override_exprs)
+ nft_expr_destroy(ctx, expr_array[i]);
+
expr_array[i] = NULL;
}
@@ -7280,6 +7255,7 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
struct nft_set_binding *binding;
struct nft_elem_priv *elem_priv;
struct nft_object *obj = NULL;
+ bool override_exprs = false;
struct nft_userdata *udata;
struct nft_data_desc desc;
enum nft_registers dreg;
@@ -7385,6 +7361,7 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
expr_array[0] = expr;
num_exprs = 1;
+ override_exprs = true;
if (set->num_exprs && set->exprs[0]->ops != expr->ops) {
err = -EOPNOTSUPP;
@@ -7413,6 +7390,7 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
}
expr_array[i] = expr;
num_exprs++;
+ override_exprs = true;
if (set->num_exprs && expr->ops != set->exprs[i]->ops) {
err = -EOPNOTSUPP;
@@ -7426,9 +7404,8 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
}
} else if (set->num_exprs > 0 &&
!(flags & NFT_SET_ELEM_INTERVAL_END)) {
- err = nft_set_elem_expr_clone(ctx, set, expr_array);
- if (err < 0)
- goto err_set_elem_expr_clone;
+ for (i = 0; i < set->num_exprs; i++)
+ expr_array[i] = set->exprs[i];
num_exprs = set->num_exprs;
}
@@ -7567,7 +7544,8 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
udata->len = ulen - 1;
nla_memcpy(&udata->data, nla[NFTA_SET_ELEM_USERDATA], ulen);
}
- err = nft_set_elem_expr_setup(ctx, &tmpl, ext, expr_array, num_exprs);
+ err = nft_set_elem_expr_setup(ctx, &tmpl, ext, expr_array, num_exprs,
+ override_exprs);
if (err < 0)
goto err_elem_free;
@@ -7675,9 +7653,11 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
err_parse_key:
nft_data_release(&elem.key.val, NFT_DATA_VALUE);
err_set_elem_expr:
- for (i = 0; i < num_exprs && expr_array[i]; i++)
- nft_expr_destroy(ctx, expr_array[i]);
-err_set_elem_expr_clone:
+ if (override_exprs) {
+ for (i = 0; i < num_exprs && expr_array[i]; i++)
+ nft_expr_destroy(ctx, expr_array[i]);
+ }
+
return err;
}
@@ -10894,6 +10874,10 @@ static void nft_set_commit_update(struct nft_ctx *ctx,
nft_ctx_update(ctx, trans);
switch (trans->msg_type) {
+ case NFT_MSG_DELSET:
+ case NFT_MSG_DESTROYSET:
+ nft_trans_set(trans)->dead = 1;
+ break;
case NFT_MSG_DELSETELEM:
te = nft_trans_container_elem(trans);
if (!te->set->ops->commit)
diff --git a/net/netfilter/nft_dynset.c b/net/netfilter/nft_dynset.c
index ee9d3e7b1ecf1..83e56b1aa8585 100644
--- a/net/netfilter/nft_dynset.c
+++ b/net/netfilter/nft_dynset.c
@@ -19,7 +19,8 @@ struct nft_dynset {
u8 sreg_key;
u8 sreg_data;
bool invert;
- bool expr;
+ bool expr:1,
+ override_exprs:1;
u8 num_exprs;
u64 timeout;
struct nft_expr *expr_array[NFT_SET_EXPR_MAX];
@@ -257,6 +258,7 @@ static int nft_dynset_init(const struct nft_ctx *ctx,
priv->num_exprs++;
priv->expr_array[0] = dynset_expr;
+ priv->override_exprs = true;
if (set->num_exprs > 1 ||
(set->num_exprs == 1 &&
@@ -289,6 +291,7 @@ static int nft_dynset_init(const struct nft_ctx *ctx,
}
priv->expr_array[i] = dynset_expr;
priv->num_exprs++;
+ priv->override_exprs = true;
if (set->num_exprs) {
if (i >= set->num_exprs) {
@@ -307,9 +310,8 @@ static int nft_dynset_init(const struct nft_ctx *ctx,
goto err_expr_free;
}
} else if (set->num_exprs > 0) {
- err = nft_set_elem_expr_clone(ctx, set, priv->expr_array);
- if (err < 0)
- return err;
+ for (i = 0; i < set->num_exprs; i++)
+ priv->expr_array[i] = set->exprs[i];
priv->num_exprs = set->num_exprs;
}
@@ -339,8 +341,10 @@ static int nft_dynset_init(const struct nft_ctx *ctx,
return 0;
err_expr_free:
- for (i = 0; i < priv->num_exprs; i++)
- nft_expr_destroy(ctx, priv->expr_array[i]);
+ if (priv->override_exprs) {
+ for (i = 0; i < priv->num_exprs; i++)
+ nft_expr_destroy(ctx, priv->expr_array[i]);
+ }
return err;
}
@@ -367,9 +371,10 @@ static void nft_dynset_destroy(const struct nft_ctx *ctx,
struct nft_dynset *priv = nft_expr_priv(expr);
int i;
- for (i = 0; i < priv->num_exprs; i++)
- nft_expr_destroy(ctx, priv->expr_array[i]);
-
+ if (priv->override_exprs) {
+ for (i = 0; i < priv->num_exprs; i++)
+ nft_expr_destroy(ctx, priv->expr_array[i]);
+ }
nf_tables_destroy_set(ctx, priv->set);
}
|
| 29/3 | 2026/08/21 12:41 | llm | kmsan-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 4884 output: 23 thoughts: 311 Thoughts: **Analyzing Netfilter's Expression Handling Optimization** Okay, so I'm looking at this patch for `nf_tables_api.c` and `nft_dynset.c`. It's all about streamlining memory management, specifically with how netfilter deals with expressions within sets. My initial thought is, "Ah, they're trying to avoid unnecessary cloning, which usually translates to a performance boost." Smart. The core idea seems to be this `override_exprs` boolean flag. If set, it means the expressions were, essentially, "taken over" or overridden. If `override_exprs` is `true`, the old expression is destroyed. If not, it just copies the pointers to the expressions. This is definitely a change in object lifecycle and reference management. We are moving away from `nft_set_elem_expr_clone` in favor of direct pointer manipulation. That's good, less overhead if we can avoid that clone. It seems to pass that `override_exprs` flag to `nft_set_elem_expr_setup`, which is interesting. It seems like it should be creating expressions, but let me think... Okay, so `nft_set_elem_expr_setup` is where things are getting a little confusing. It's doing something like this: ```c elem_expr->size += expr_array[i]->ops->size; if (override_exprs) nft_expr_destroy(ctx, expr_array[i]); expr_array[i] = NULL; ``` Hmm... if `override_exprs` is `false`, it *doesn't* destroy the expression. This seems off. `nft_set_elem_expr_setup` is supposed to *setup* the expressions in the element, right? So if it's setting them up, it *must* be cloning them or creating them from scratch. I guess they are using a hybrid approach, cloning only when necessary. But it should then be *destroying* them when it's done. I need to confirm if it clones the expressions. Let me go check the source code for `nft_set_elem_expr_setup` and see what it's really doing. |
| 30/3 | 2026/08/21 12:41 | tool | grepper |
0mArgs:{
"Expression": "nft_set_elem_expr_setup"
}Results: {
"Output": "net/netfilter/nf_tables_api.c=6915=static void nft_trans_elems_destroy(const struct nft_ctx *ctx,\n--\nnet/netfilter/nf_tables_api.c-6923-\nnet/netfilter/nf_tables_api.c:6924:static int nft_set_elem_expr_setup(struct nft_ctx *ctx,\nnet/netfilter/nf_tables_api.c-6925-\t\t\t\t const struct nft_set_ext_tmpl *tmpl,\n--\nnet/netfilter/nf_tables_api.c=7245=static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,\n--\nnet/netfilter/nf_tables_api.c-7546-\t}\nnet/netfilter/nf_tables_api.c:7547:\terr = nft_set_elem_expr_setup(ctx, \u0026tmpl, ext, expr_array, num_exprs,\nnet/netfilter/nf_tables_api.c-7548-\t\t\t\t override_exprs);\n"
} |
| 31/3 | 2026/08/21 12:41 | llm | kmsan-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 5979 output: 41 thoughts: 15 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience and written in the first person: **Diving into `nft_set_elem_expr_setup`** Okay, let's take a look at `nft_set_elem_expr_setup`. My initial hunch is this is the function responsible for setting up the expression associated with an element within an NFTables set. It's likely a crucial part of the set management infrastructure. I'm expecting to see handling of data types, potential key/payload parsing, and perhaps some optimization considerations for different element formats. I'm immediately interested in how it deals with the various data types that NFTables supports for set elements – IPv4 addresses, IPv6 addresses, ports, integers, strings, etc. How does it validate the input and ensure type compatibility? Does it have a switch statement or a more sophisticated dispatch mechanism? I'm betting on a well-designed structure to handle the type-specific logic cleanly. Furthermore, I'm curious about the interaction with the underlying data structures within the kernel for the set itself. Is it allocating memory for the element expression? How does it integrate with the hash table or radix tree used to store the set elements? Is there any caching or pre-calculation being done to improve performance? I'll be keeping an eye out for any memory management details and potential locking considerations, as set operations need to be thread-safe. I'm also anticipating some form of error handling. What happens if the element expression is invalid, or if there's a problem allocating memory? Are specific error codes being returned? How granular is the error reporting? The quality of the error handling will give me a good indication of the overall robustness of this component. Finally, I'll be looking for any hints of optimization techniques. Does it attempt to compact data, or use specialized instructions where possible? How does it handle large sets, and are there any scalability considerations? |
| 32/3 | 2026/08/21 12:41 | tool | read-file |
0mArgs:{
"File": "net/netfilter/nf_tables_api.c",
"FirstLine": 6924,
"LineCount": 50
}Results: {
"Contents": "6924:\tstatic int nft_set_elem_expr_setup(struct nft_ctx *ctx,\n6925:\t\t\t\t\t const struct nft_set_ext_tmpl *tmpl,\n6926:\t\t\t\t\t const struct nft_set_ext *ext,\n6927:\t\t\t\t\t struct nft_expr *expr_array[],\n6928:\t\t\t\t\t u32 num_exprs, bool override_exprs)\n6929:\t{\n6930:\t\tstruct nft_set_elem_expr *elem_expr = nft_set_ext_expr(ext);\n6931:\t\tu32 len = sizeof(struct nft_set_elem_expr);\n6932:\t\tstruct nft_expr *expr;\n6933:\t\tint i, err;\n6934:\t\n6935:\t\tif (num_exprs == 0)\n6936:\t\t\treturn 0;\n6937:\t\n6938:\t\tfor (i = 0; i \u003c num_exprs; i++)\n6939:\t\t\tlen += expr_array[i]-\u003eops-\u003esize;\n6940:\t\n6941:\t\tif (nft_set_ext_check(tmpl, NFT_SET_EXT_EXPRESSIONS, len) \u003c 0)\n6942:\t\t\treturn -EINVAL;\n6943:\t\n6944:\t\tfor (i = 0; i \u003c num_exprs; i++) {\n6945:\t\t\texpr = nft_setelem_expr_at(elem_expr, elem_expr-\u003esize);\n6946:\t\t\terr = nft_expr_clone(expr, expr_array[i], GFP_KERNEL_ACCOUNT);\n6947:\t\t\tif (err \u003c 0)\n6948:\t\t\t\tgoto err_elem_expr_setup;\n6949:\t\n6950:\t\t\telem_expr-\u003esize += expr_array[i]-\u003eops-\u003esize;\n6951:\t\t\tif (override_exprs)\n6952:\t\t\t\tnft_expr_destroy(ctx, expr_array[i]);\n6953:\t\t\texpr_array[i] = NULL;\n6954:\t\t}\n6955:\t\n6956:\t\treturn 0;\n6957:\t\n6958:\terr_elem_expr_setup:\n6959:\t\tfor (; i \u003c num_exprs; i++) {\n6960:\t\t\tif (override_exprs)\n6961:\t\t\t\tnft_expr_destroy(ctx, expr_array[i]);\n6962:\t\n6963:\t\t\texpr_array[i] = NULL;\n6964:\t\t}\n6965:\t\n6966:\t\treturn -ENOMEM;\n6967:\t}\n6968:\t\n6969:\tstruct nft_set_ext *nft_set_catchall_lookup(const struct net *net,\n6970:\t\t\t\t\t\t const struct nft_set *set)\n6971:\t{\n6972:\t\tstruct nft_set_elem_catchall *catchall;\n6973:\t\tu8 genmask = nft_genmask_cur(net);\n"
} |
| 33/3 | 2026/08/21 12:41 | llm | kmsan-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 7245 output: 41 thoughts: 100 Thoughts: **My Observations on Expression Cloning in Netfilter Sets** Right, so `nft_set_elem_expr_setup` is now handling the cloning of expressions directly into the set element. This is a significant change. Previously, I recall `nft_add_set_elem` would clone those expressions into an `expr_array` first, using `nft_set_elem_expr_clone`. Then, it seems, `nft_set_elem_expr_setup` would *then* clone them again? That sounds inefficient, and frankly, a bit redundant. I need to double-check my mental model here. The old code for `nft_set_elem_expr_clone` should provide some clarity on why we had this extra, potentially unnecessary, layer of cloning. Let's see what that looks like. |
| 34/3 | 2026/08/21 12:41 | tool | read-file |
0mArgs:{
"File": "net/netfilter/nf_tables_api.c",
"FirstLine": 6910,
"LineCount": 20
}Results: {
"Contents": "6910:\t\t\tnft_set_elem_expr_destroy(ctx, nft_set_ext_expr(ext));\n6911:\t\n6912:\t\tkfree(elem_priv);\n6913:\t}\n6914:\t\n6915:\tstatic void nft_trans_elems_destroy(const struct nft_ctx *ctx,\n6916:\t\t\t\t\t const struct nft_trans_elem *te)\n6917:\t{\n6918:\t\tint i;\n6919:\t\n6920:\t\tfor (i = 0; i \u003c te-\u003enelems; i++)\n6921:\t\t\tnf_tables_set_elem_destroy(ctx, te-\u003eset, te-\u003eelems[i].priv);\n6922:\t}\n6923:\t\n6924:\tstatic int nft_set_elem_expr_setup(struct nft_ctx *ctx,\n6925:\t\t\t\t\t const struct nft_set_ext_tmpl *tmpl,\n6926:\t\t\t\t\t const struct nft_set_ext *ext,\n6927:\t\t\t\t\t struct nft_expr *expr_array[],\n6928:\t\t\t\t\t u32 num_exprs, bool override_exprs)\n6929:\t{\n"
} |
| 35/3 | 2026/08/21 12:41 | llm | kmsan-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 7886 output: 21 thoughts: 886 Thoughts: **Analyzing the Expression Cloning Optimization** Okay, so I need to go over this `nft_set_elem_expr_clone` function from the diff. Initially, it seems they are cloning the expressions from the set and storing them in `expr_array`. Specifically, `kzalloc` is being used to allocate memory and the `nft_expr_clone` function is used for the copying. Then, I'm reminded of how `nft_set_elem_expr_setup` was utilizing `expr_array`. It looks like it was cloning these *clones* again into the element and destroying the original clone afterward. That's a textbook double-clone scenario! We had a temporary copy that was ultimately discarded. The patch cleans this up significantly. The patch's optimization strategy is to pass the original expressions directly in `expr_array` when possible. If the set's expressions are *not* being overridden by a user-provided expression, `nft_set_elem_expr_setup` clones these directly into the element. If there's an override, that new object from parsing is already there and copied, and the temp allocation is destroyed. This directly addresses the double-clone problem, reducing the memory footprint and improving performance. I'm making sure to keep the memory management logic straight here. The `override_exprs` flag is key. If true, the `expr_array` contains newly allocated objects, freshly parsed. `nft_set_elem_expr_setup` clones them and then frees the memory. If false, it's pointers to the *set's* default expressions. These are *cloned* into the element but the originals in `expr_array` remain, because those expressions are part of the set, and shouldn't be touched by setup. So, this is a clean memory management and object lifecycle optimization. Critically, it *doesn't* introduce any risk of uninitialized memory. `nft_expr_clone` is still responsible for correctly initializing the copied data within the element itself. Now, let me make sure... `nft_setelem_expr_at` returns a pointer to the element's extension area. I need to confirm whether this area is correctly zeroed before the copy takes place. I need to trace back from `elem_expr` to `nft_set_ext_expr(ext)`. `ext` is from `nft_set_elem_init` or similar. I need to make sure that the area is initialized properly. I'll need to double-check that. That's the one thing that will cause a problem here! I'm going to follow this up to make sure it's valid. |
| 36/3 | 2026/08/21 12:42 | tool | grepper |
0mArgs:{
"Expression": "nft_set_elem_init"
}Results: {
"Output": "include/net/netfilter/nf_tables.h=864=struct nft_expr *nft_set_elem_expr_alloc(const struct nft_ctx *ctx,\n--\ninclude/net/netfilter/nf_tables.h-867-\ninclude/net/netfilter/nf_tables.h:868:struct nft_elem_priv *nft_set_elem_init(const struct nft_set *set,\ninclude/net/netfilter/nf_tables.h-869-\t\t\t\t\tconst struct nft_set_ext_tmpl *tmpl,\n--\nnet/netfilter/nf_tables_api.c=6774=static int nft_set_ext_memcpy(const struct nft_set_ext_tmpl *tmpl, u8 id,\n--\nnet/netfilter/nf_tables_api.c-6784-\nnet/netfilter/nf_tables_api.c:6785:struct nft_elem_priv *nft_set_elem_init(const struct nft_set *set,\nnet/netfilter/nf_tables_api.c-6786-\t\t\t\t\tconst struct nft_set_ext_tmpl *tmpl,\n--\nnet/netfilter/nf_tables_api.c=7245=static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,\n--\nnet/netfilter/nf_tables_api.c-7522-\nnet/netfilter/nf_tables_api.c:7523:\telem.priv = nft_set_elem_init(set, \u0026tmpl, elem.key.val.data,\nnet/netfilter/nf_tables_api.c-7524-\t\t\t\t elem.key_end.val.data, elem.data.val.data,\n--\nnet/netfilter/nf_tables_api.c=7825=static int nft_del_setelem(struct nft_ctx *ctx, struct nft_set *set,\n--\nnet/netfilter/nf_tables_api.c-7881-\terr = -ENOMEM;\nnet/netfilter/nf_tables_api.c:7882:\telem.priv = nft_set_elem_init(set, \u0026tmpl, elem.key.val.data,\nnet/netfilter/nf_tables_api.c-7883-\t\t\t\t elem.key_end.val.data, NULL, 0, 0,\n--\nnet/netfilter/nft_dynset.c=56=struct nft_elem_priv *nft_dynset_new(struct nft_set *set,\n--\nnet/netfilter/nft_dynset.c-68-\ttimeout = priv-\u003etimeout ? : READ_ONCE(set-\u003etimeout);\nnet/netfilter/nft_dynset.c:69:\telem_priv = nft_set_elem_init(set, \u0026priv-\u003etmpl,\nnet/netfilter/nft_dynset.c-70-\t\t\t\t \u0026regs-\u003edata[priv-\u003esreg_key], NULL,\n"
} |
| 37/3 | 2026/08/21 12:42 | llm | kmsan-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 10097 output: 41 thoughts: 13 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience: **Diving into `nft_set_elem_init`** Alright, let's get down to brass tacks. Time to take a look at `nft_set_elem_init`. Given the context, I'm expecting this function is responsible for the initialization of an element within an NFTables set. It's the building block, the ground floor for defining how data gets stored and used within the rule structure. I'll need to understand how the data structures are defined, memory is allocated (or re-used if possible), and what checks are performed to ensure consistency and prevent errors. I'm especially interested in how it handles different element types – whether it’s integer, IP addresses, strings, or more complex data structures. What's the strategy for dealing with potential collisions or overlaps, if any? And of course, performance is key – how efficient is this initialization process, especially when dealing with large sets and frequent additions/deletions? Gotta keep an eye on those nitty-gritty details to make sure this is tight! |
| 38/3 | 2026/08/21 12:42 | tool | read-file |
0mArgs:{
"File": "net/netfilter/nf_tables_api.c",
"FirstLine": 6785,
"LineCount": 40
}Results: {
"Contents": "6785:\tstruct nft_elem_priv *nft_set_elem_init(const struct nft_set *set,\n6786:\t\t\t\t\t\tconst struct nft_set_ext_tmpl *tmpl,\n6787:\t\t\t\t\t\tconst u32 *key, const u32 *key_end,\n6788:\t\t\t\t\t\tconst u32 *data,\n6789:\t\t\t\t\t\tu64 timeout, u64 expiration, gfp_t gfp)\n6790:\t{\n6791:\t\tstruct nft_set_ext *ext;\n6792:\t\tvoid *elem;\n6793:\t\n6794:\t\telem = kzalloc(set-\u003eops-\u003eelemsize + tmpl-\u003elen, gfp);\n6795:\t\tif (elem == NULL)\n6796:\t\t\treturn ERR_PTR(-ENOMEM);\n6797:\t\n6798:\t\text = nft_set_elem_ext(set, elem);\n6799:\t\tnft_set_ext_init(ext, tmpl);\n6800:\t\n6801:\t\tif (nft_set_ext_exists(ext, NFT_SET_EXT_KEY) \u0026\u0026\n6802:\t\t nft_set_ext_memcpy(tmpl, NFT_SET_EXT_KEY,\n6803:\t\t\t\t nft_set_ext_key(ext), key, set-\u003eklen) \u003c 0)\n6804:\t\t\tgoto err_ext_check;\n6805:\t\n6806:\t\tif (nft_set_ext_exists(ext, NFT_SET_EXT_KEY_END) \u0026\u0026\n6807:\t\t nft_set_ext_memcpy(tmpl, NFT_SET_EXT_KEY_END,\n6808:\t\t\t\t nft_set_ext_key_end(ext), key_end, set-\u003eklen) \u003c 0)\n6809:\t\t\tgoto err_ext_check;\n6810:\t\n6811:\t\tif (nft_set_ext_exists(ext, NFT_SET_EXT_DATA) \u0026\u0026\n6812:\t\t nft_set_ext_memcpy(tmpl, NFT_SET_EXT_DATA,\n6813:\t\t\t\t nft_set_ext_data(ext), data, set-\u003edlen) \u003c 0)\n6814:\t\t\tgoto err_ext_check;\n6815:\t\n6816:\t\tif (nft_set_ext_exists(ext, NFT_SET_EXT_TIMEOUT)) {\n6817:\t\t\tnft_set_ext_timeout(ext)-\u003etimeout = timeout;\n6818:\t\n6819:\t\t\tif (expiration == 0)\n6820:\t\t\t\texpiration = timeout;\n6821:\t\n6822:\t\t\tnft_set_ext_timeout(ext)-\u003eexpiration = get_jiffies_64() + expiration;\n6823:\t\t}\n6824:\t\n"
} |
| 39/3 | 2026/08/21 12:42 | llm | kmsan-evaluator |
0mModel:gemini-3.1-pro-preview Args: null Results: null Tokens: input: 11119 output: 219 thoughts: 1097 Thoughts: **Patch Analysis: Memory Management Fixes in Netfilter Sets** Okay, let's break this down. My initial thought was about the removal of that `kzalloc` in `nft_set_elem_expr_clone`. But that was just for a temporary clone that's bypassed now. The crucial point is that the *actual* element memory is still zeroed during initialization via `kzalloc`. So, no immediate risk there. I did a quick check on `nft_expr_clone` just in case, but that copies from an *initialized* original expression. Then I moved on to the changes in `nft_set_commit_update`. Setting `dead = 1` on deleted sets... sounds like a use-after-free protection. Makes sense. Digging further, I looked at `nft_dynset_init` and `nft_dynset_destroy`. It's now storing direct pointers to set expressions, instead of cloning them, with this `override_exprs` flag to signal whether the set expression's expressions should be destroyed or not. That strongly suggests a double-free or UAF bug fix: we're preventing the dynset expression from destroying the set expressions when they're not owned by the dynset expression. So, in summary, this patch is fixing: 1. Expression cloning in `nft_add_set_elem`. 2. Double-free/UAF in `nft_dynset_destroy`. 3. Setting the `dead` flag on deleted sets. I'm confident that none of these changes introduce *or* expose any uninitialized memory risks. These are memory management fixes, pure and simple. KASAN is the tool for these kinds of bugs. KMSAN isn't needed here. Now, let's double-check any possible uninitialized memory exposure to userspace. The expressions themselves can get dumped to userspace via netlink. The element memory gets `kzalloc`'ed in `nft_set_elem_init`, meaning it's all zeroed. The expressions are cloned into that zeroed memory with `nft_expr_clone`, which means, because the expression was already initialized and likely zero-padded, we're not dealing with uninitialized memory. Also, this patch *doesn't* change what gets stored in the element, only *how* it gets there. Therefore, no, there are no uninitialized memory concerns here. **I'm setting NeedsKMSAN=false.** This is all about fixing object lifecycle problems and potential memory leaks, which are well handled by KASAN. |
| 40/3 | 2026/08/21 12:42 | tool | set-results |
0mArgs:{
"KMSANReasoning": "The patch series refactors the lifecycle and cloning of netfilter set expressions (`nft_expr`) to fix memory management issues (likely double-frees or use-after-frees). It avoids creating intermediate clones of expressions when adding elements to a set or initializing a dynset, instead copying pointers and using a new `override_exprs` flag to track ownership and determine if the expressions should be destroyed. It also sets a `dead` flag on deleted sets during commit updates. \n\nThese changes address object lifecycle bugs (UAF, double-free) which are reliably detected by KASAN. The memory for the set elements themselves continues to be allocated with `kzalloc` (in `nft_set_elem_init`), ensuring all fields and padding are fully zeroed. No new structures are introduced, and no uninitialized memory is exposed to userspace or used in control flow. Therefore, a dedicated KMSAN fuzzing session is not justified.",
"NeedsKMSAN": false
}Results: {
"KMSANReasoning": "The patch series refactors the lifecycle and cloning of netfilter set expressions (`nft_expr`) to fix memory management issues (likely double-frees or use-after-frees). It avoids creating intermediate clones of expressions when adding elements to a set or initializing a dynset, instead copying pointers and using a new `override_exprs` flag to track ownership and determine if the expressions should be destroyed. It also sets a `dead` flag on deleted sets during commit updates. \n\nThese changes address object lifecycle bugs (UAF, double-free) which are reliably detected by KASAN. The memory for the set elements themselves continues to be allocated with `kzalloc` (in `nft_set_elem_init`), ensuring all fields and padding are fully zeroed. No new structures are introduced, and no uninitialized memory is exposed to userspace or used in control flow. Therefore, a dedicated KMSAN fuzzing session is not justified.",
"NeedsKMSAN": false
} |
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