AI Trajectory

null

{
  "EnableConfigs": [
    "IP_SCTP"
  ],
  "FocusSymbols": [
    "sctp_auth_calculate_hmac",
    "sctp_packet_transmit",
    "sctp_sf_do_5_1D_ce",
    "sctp_sf_do_5_2_4_dupcook",
    "sctp_sf_eat_auth"
  ],
  "Reasoning": "The patch modifies SCTP authentication HMAC calculation to properly handle and propagate memory allocation failures (-ENOMEM). It updates the return type of sctp_auth_calculate_hmac and modifies callers in sctp_packet_pack and sctp_sf_authenticate to handle the error, preventing potential null pointer dereferences or silent failures. This is a functional change in core networking logic that should be fuzzed.",
  "WorthFuzzing": true
}

null

{
  "PatchDiff": "commit dba0c3f825408f18199e7f3eb0f8020676f331a5\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Tue Aug 4 07:54:28 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/include/net/sctp/auth.h b/include/net/sctp/auth.h\nindex 6f2cd562b1de6..eeb3297fe97d3 100644\n--- a/include/net/sctp/auth.h\n+++ b/include/net/sctp/auth.h\n@@ -83,9 +83,9 @@ int sctp_auth_send_cid(enum sctp_cid chunk,\n \t\t       const struct sctp_association *asoc);\n int sctp_auth_recv_cid(enum sctp_cid chunk,\n \t\t       const struct sctp_association *asoc);\n-void sctp_auth_calculate_hmac(const struct sctp_association *asoc,\n-\t\t\t      struct sk_buff *skb, struct sctp_auth_chunk *auth,\n-\t\t\t      struct sctp_shared_key *ep_key, gfp_t gfp);\n+int sctp_auth_calculate_hmac(const struct sctp_association *asoc,\n+\t\t\t     struct sk_buff *skb, struct sctp_auth_chunk *auth,\n+\t\t\t     struct sctp_shared_key *ep_key, gfp_t gfp);\n void sctp_auth_shkey_release(struct sctp_shared_key *sh_key);\n void sctp_auth_shkey_hold(struct sctp_shared_key *sh_key);\n \ndiff --git a/net/sctp/auth.c b/net/sctp/auth.c\nindex c901d373af803..6de66f56c41ce 100644\n--- a/net/sctp/auth.c\n+++ b/net/sctp/auth.c\n@@ -613,9 +613,9 @@ int sctp_auth_recv_cid(enum sctp_cid chunk, const struct sctp_association *asoc)\n  *    zero (as shown in Figure 6) followed by all chunks that are placed\n  *    after the AUTH chunk in the SCTP packet.\n  */\n-void sctp_auth_calculate_hmac(const struct sctp_association *asoc,\n-\t\t\t      struct sk_buff *skb, struct sctp_auth_chunk *auth,\n-\t\t\t      struct sctp_shared_key *ep_key, gfp_t gfp)\n+int sctp_auth_calculate_hmac(const struct sctp_association *asoc,\n+\t\t\t     struct sk_buff *skb, struct sctp_auth_chunk *auth,\n+\t\t\t     struct sctp_shared_key *ep_key, gfp_t gfp)\n {\n \tstruct sctp_auth_bytes *asoc_key;\n \t__u16 key_id, hmac_id;\n@@ -636,7 +636,7 @@ void sctp_auth_calculate_hmac(const struct sctp_association *asoc,\n \t\t/* ep_key can't be NULL here */\n \t\tasoc_key = sctp_auth_asoc_create_secret(asoc, ep_key, gfp);\n \t\tif (!asoc_key)\n-\t\t\treturn;\n+\t\t\treturn -ENOMEM;\n \n \t\tfree_key = 1;\n \t}\n@@ -654,6 +654,8 @@ void sctp_auth_calculate_hmac(const struct sctp_association *asoc,\n \n \tif (free_key)\n \t\tsctp_auth_key_put(asoc_key);\n+\n+\treturn 0;\n }\n \n /* API Helpers */\ndiff --git a/net/sctp/output.c b/net/sctp/output.c\nindex 23e96305cad7c..3d7ead9d40e19 100644\n--- a/net/sctp/output.c\n+++ b/net/sctp/output.c\n@@ -517,8 +517,14 @@ static int sctp_packet_pack(struct sctp_packet *packet,\n \t\t}\n \n \t\tif (auth) {\n-\t\t\tsctp_auth_calculate_hmac(tp-\u003easoc, nskb, auth,\n-\t\t\t\t\t\t packet-\u003eauth-\u003eshkey, gfp);\n+\t\t\tif (sctp_auth_calculate_hmac(tp-\u003easoc, nskb, auth,\n+\t\t\t\t\t\t     packet-\u003eauth-\u003eshkey, gfp)) {\n+\t\t\t\tsctp_chunk_free(packet-\u003eauth);\n+\t\t\t\tpacket-\u003eauth = NULL;\n+\t\t\t\tif (gso)\n+\t\t\t\t\tkfree_skb(nskb);\n+\t\t\t\treturn -ENOMEM;\n+\t\t\t}\n \t\t\t/* free auth if no more chunks, or add it back */\n \t\t\tif (list_empty(\u0026packet-\u003echunk_list))\n \t\t\t\tsctp_chunk_free(packet-\u003eauth);\n@@ -619,7 +625,7 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)\n \n \t/* pack up chunks */\n \tpkt_count = sctp_packet_pack(packet, head, gso, gfp);\n-\tif (!pkt_count) {\n+\tif (pkt_count \u003c= 0) {\n \t\tkfree_skb(head);\n \t\tgoto out;\n \t}\ndiff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c\nindex 708fa07d5fffc..e19881c90b499 100644\n--- a/net/sctp/sm_statefuns.c\n+++ b/net/sctp/sm_statefuns.c\n@@ -637,13 +637,17 @@ enum sctp_disposition sctp_sf_do_5_1C_ack(struct net *net,\n \treturn SCTP_DISPOSITION_CONSUME;\n }\n \n-static bool sctp_auth_chunk_verify(struct net *net, struct sctp_chunk *chunk,\n-\t\t\t\t   const struct sctp_association *asoc)\n+static enum sctp_ierror sctp_auth_chunk_verify(struct net *net,\n+\t\t\t\t\t       struct sctp_chunk *chunk,\n+\t\t\t\t\t       const struct sctp_association *asoc)\n {\n \tstruct sctp_chunk auth;\n \n-\tif (!chunk-\u003eauth_chunk)\n-\t\treturn !sctp_auth_recv_cid(chunk-\u003echunk_hdr-\u003etype, asoc);\n+\tif (!chunk-\u003eauth_chunk) {\n+\t\tif (sctp_auth_recv_cid(chunk-\u003echunk_hdr-\u003etype, asoc))\n+\t\t\treturn SCTP_IERROR_BAD_SIG;\n+\t\treturn SCTP_IERROR_NO_ERROR;\n+\t}\n \n \t/* SCTP-AUTH:  auth_chunk pointer is only set when the cookie-echo\n \t * is supposed to be authenticated and we have to do delayed\n@@ -654,7 +658,7 @@ static bool sctp_auth_chunk_verify(struct net *net, struct sctp_chunk *chunk,\n \n \t/* Make sure that we and the peer are AUTH capable */\n \tif (!net-\u003esctp.auth_enable || !asoc-\u003epeer.auth_capable)\n-\t\treturn false;\n+\t\treturn SCTP_IERROR_BAD_SIG;\n \n \t/* set-up our fake chunk so that we can process it */\n \tauth.skb = chunk-\u003eauth_chunk;\n@@ -666,7 +670,7 @@ static bool sctp_auth_chunk_verify(struct net *net, struct sctp_chunk *chunk,\n \tskb_pull(chunk-\u003eauth_chunk, sizeof(struct sctp_chunkhdr));\n \tauth.transport = chunk-\u003etransport;\n \n-\treturn sctp_sf_authenticate(asoc, \u0026auth) == SCTP_IERROR_NO_ERROR;\n+\treturn sctp_sf_authenticate(asoc, \u0026auth);\n }\n \n /*\n@@ -826,8 +830,11 @@ enum sctp_disposition sctp_sf_do_5_1D_ce(struct net *net,\n \tif (error)\n \t\tgoto nomem_init;\n \n-\tif (!sctp_auth_chunk_verify(net, chunk, new_asoc)) {\n+\terror = sctp_auth_chunk_verify(net, chunk, new_asoc);\n+\tif (error != SCTP_IERROR_NO_ERROR) {\n \t\tsctp_association_free(new_asoc);\n+\t\tif (error == SCTP_IERROR_NOMEM)\n+\t\t\treturn SCTP_DISPOSITION_NOMEM;\n \t\treturn sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);\n \t}\n \n@@ -1889,6 +1896,7 @@ static enum sctp_disposition sctp_sf_do_dupcook_a(\n {\n \tstruct sctp_init_chunk *peer_init;\n \tenum sctp_disposition disposition;\n+\tenum sctp_ierror error;\n \tstruct sctp_ulpevent *ev;\n \tstruct sctp_chunk *repl;\n \tstruct sctp_chunk *err;\n@@ -1904,8 +1912,12 @@ static enum sctp_disposition sctp_sf_do_dupcook_a(\n \tif (sctp_auth_asoc_init_active_key(new_asoc, GFP_ATOMIC))\n \t\tgoto nomem;\n \n-\tif (!sctp_auth_chunk_verify(net, chunk, new_asoc))\n+\terror = sctp_auth_chunk_verify(net, chunk, new_asoc);\n+\tif (error != SCTP_IERROR_NO_ERROR) {\n+\t\tif (error == SCTP_IERROR_NOMEM)\n+\t\t\treturn SCTP_DISPOSITION_NOMEM;\n \t\treturn SCTP_DISPOSITION_DISCARD;\n+\t}\n \n \t/* Make sure no new addresses are being added during the\n \t * restart.  Though this is a pretty complicated attack\n@@ -2011,6 +2023,7 @@ static enum sctp_disposition sctp_sf_do_dupcook_b(\n \t\t\t\t\tstruct sctp_association *new_asoc)\n {\n \tstruct sctp_init_chunk *peer_init;\n+\tenum sctp_ierror error;\n \tstruct sctp_chunk *repl;\n \n \t/* new_asoc is a brand-new association, so these are not yet\n@@ -2024,8 +2037,12 @@ static enum sctp_disposition sctp_sf_do_dupcook_b(\n \tif (sctp_auth_asoc_init_active_key(new_asoc, GFP_ATOMIC))\n \t\tgoto nomem;\n \n-\tif (!sctp_auth_chunk_verify(net, chunk, new_asoc))\n+\terror = sctp_auth_chunk_verify(net, chunk, new_asoc);\n+\tif (error != SCTP_IERROR_NO_ERROR) {\n+\t\tif (error == SCTP_IERROR_NOMEM)\n+\t\t\treturn SCTP_DISPOSITION_NOMEM;\n \t\treturn SCTP_DISPOSITION_DISCARD;\n+\t}\n \n \tsctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,\n \t\t\tSCTP_STATE(SCTP_STATE_ESTABLISHED));\n@@ -2118,6 +2135,7 @@ static enum sctp_disposition sctp_sf_do_dupcook_d(\n \t\t\t\t\tstruct sctp_association *new_asoc)\n {\n \tstruct sctp_ulpevent *ev = NULL, *ai_ev = NULL, *auth_ev = NULL;\n+\tenum sctp_ierror error;\n \tstruct sctp_chunk *repl;\n \n \t/* Clarification from Implementor's Guide:\n@@ -2127,8 +2145,12 @@ static enum sctp_disposition sctp_sf_do_dupcook_d(\n \t * a COOKIE ACK.\n \t */\n \n-\tif (!sctp_auth_chunk_verify(net, chunk, asoc))\n+\terror = sctp_auth_chunk_verify(net, chunk, asoc);\n+\tif (error != SCTP_IERROR_NO_ERROR) {\n+\t\tif (error == SCTP_IERROR_NOMEM)\n+\t\t\treturn SCTP_DISPOSITION_NOMEM;\n \t\treturn SCTP_DISPOSITION_DISCARD;\n+\t}\n \n \t/* Don't accidentally move back into established state. */\n \tif (asoc-\u003estate \u003c SCTP_STATE_ESTABLISHED) {\n@@ -4455,9 +4477,12 @@ static enum sctp_ierror sctp_sf_authenticate(\n \n \tmemset(digest, 0, sig_len);\n \n-\tsctp_auth_calculate_hmac(asoc, chunk-\u003eskb,\n-\t\t\t\t (struct sctp_auth_chunk *)chunk-\u003echunk_hdr,\n-\t\t\t\t sh_key, GFP_ATOMIC);\n+\tif (sctp_auth_calculate_hmac(asoc, chunk-\u003eskb,\n+\t\t\t\t     (struct sctp_auth_chunk *)chunk-\u003echunk_hdr,\n+\t\t\t\t     sh_key, GFP_ATOMIC)) {\n+\t\tkfree(save_digest);\n+\t\treturn SCTP_IERROR_NOMEM;\n+\t}\n \n \t/* Discard the packet if the digests do not match */\n \tif (crypto_memneq(save_digest, digest, sig_len)) {\n"
}

best-expensive

null

{
  "EnableConfigs": [
    "IP_SCTP"
  ],
  "FocusSymbols": [
    "sctp_auth_calculate_hmac",
    "sctp_packet_transmit",
    "sctp_sf_do_5_1D_ce",
    "sctp_sf_do_5_2_4_dupcook",
    "sctp_sf_eat_auth"
  ],
  "Reasoning": "The patch modifies SCTP authentication HMAC calculation to properly handle and propagate memory allocation failures (-ENOMEM). It updates the return type of sctp_auth_calculate_hmac and modifies callers in sctp_packet_pack and sctp_sf_authenticate to handle the error, preventing potential null pointer dereferences or silent failures. This is a functional change in core networking logic that should be fuzzed.",
  "WorthFuzzing": true
}

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.

For your convenience, here is the diff of the changes:
commit dba0c3f825408f18199e7f3eb0f8020676f331a5
Author: syz-cluster <triage@syzkaller.com>
Date:   Tue Aug 4 07:54:28 2026 +0000

    syz-cluster: applied patch under review

diff --git a/include/net/sctp/auth.h b/include/net/sctp/auth.h
index 6f2cd562b1de6..eeb3297fe97d3 100644
--- a/include/net/sctp/auth.h
+++ b/include/net/sctp/auth.h
@@ -83,9 +83,9 @@ int sctp_auth_send_cid(enum sctp_cid chunk,
 		       const struct sctp_association *asoc);
 int sctp_auth_recv_cid(enum sctp_cid chunk,
 		       const struct sctp_association *asoc);
-void sctp_auth_calculate_hmac(const struct sctp_association *asoc,
-			      struct sk_buff *skb, struct sctp_auth_chunk *auth,
-			      struct sctp_shared_key *ep_key, gfp_t gfp);
+int sctp_auth_calculate_hmac(const struct sctp_association *asoc,
+			     struct sk_buff *skb, struct sctp_auth_chunk *auth,
+			     struct sctp_shared_key *ep_key, gfp_t gfp);
 void sctp_auth_shkey_release(struct sctp_shared_key *sh_key);
 void sctp_auth_shkey_hold(struct sctp_shared_key *sh_key);
 
diff --git a/net/sctp/auth.c b/net/sctp/auth.c
index c901d373af803..6de66f56c41ce 100644
--- a/net/sctp/auth.c
+++ b/net/sctp/auth.c
@@ -613,9 +613,9 @@ int sctp_auth_recv_cid(enum sctp_cid chunk, const struct sctp_association *asoc)
  *    zero (as shown in Figure 6) followed by all chunks that are placed
  *    after the AUTH chunk in the SCTP packet.
  */
-void sctp_auth_calculate_hmac(const struct sctp_association *asoc,
-			      struct sk_buff *skb, struct sctp_auth_chunk *auth,
-			      struct sctp_shared_key *ep_key, gfp_t gfp)
+int sctp_auth_calculate_hmac(const struct sctp_association *asoc,
+			     struct sk_buff *skb, struct sctp_auth_chunk *auth,
+			     struct sctp_shared_key *ep_key, gfp_t gfp)
 {
 	struct sctp_auth_bytes *asoc_key;
 	__u16 key_id, hmac_id;
@@ -636,7 +636,7 @@ void sctp_auth_calculate_hmac(const struct sctp_association *asoc,
 		/* ep_key can't be NULL here */
 		asoc_key = sctp_auth_asoc_create_secret(asoc, ep_key, gfp);
 		if (!asoc_key)
-			return;
+			return -ENOMEM;
 
 		free_key = 1;
 	}
@@ -654,6 +654,8 @@ void sctp_auth_calculate_hmac(const struct sctp_association *asoc,
 
 	if (free_key)
 		sctp_auth_key_put(asoc_key);
+
+	return 0;
 }
 
 /* API Helpers */
diff --git a/net/sctp/output.c b/net/sctp/output.c
index 23e96305cad7c..3d7ead9d40e19 100644
--- a/net/sctp/output.c
+++ b/net/sctp/output.c
@@ -517,8 +517,14 @@ static int sctp_packet_pack(struct sctp_packet *packet,
 		}
 
 		if (auth) {
-			sctp_auth_calculate_hmac(tp->asoc, nskb, auth,
-						 packet->auth->shkey, gfp);
+			if (sctp_auth_calculate_hmac(tp->asoc, nskb, auth,
+						     packet->auth->shkey, gfp)) {
+				sctp_chunk_free(packet->auth);
+				packet->auth = NULL;
+				if (gso)
+					kfree_skb(nskb);
+				return -ENOMEM;
+			}
 			/* free auth if no more chunks, or add it back */
 			if (list_empty(&packet->chunk_list))
 				sctp_chunk_free(packet->auth);
@@ -619,7 +625,7 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
 
 	/* pack up chunks */
 	pkt_count = sctp_packet_pack(packet, head, gso, gfp);
-	if (!pkt_count) {
+	if (pkt_count <= 0) {
 		kfree_skb(head);
 		goto out;
 	}
diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
index 708fa07d5fffc..e19881c90b499 100644
--- a/net/sctp/sm_statefuns.c
+++ b/net/sctp/sm_statefuns.c
@@ -637,13 +637,17 @@ enum sctp_disposition sctp_sf_do_5_1C_ack(struct net *net,
 	return SCTP_DISPOSITION_CONSUME;
 }
 
-static bool sctp_auth_chunk_verify(struct net *net, struct sctp_chunk *chunk,
-				   const struct sctp_association *asoc)
+static enum sctp_ierror sctp_auth_chunk_verify(struct net *net,
+					       struct sctp_chunk *chunk,
+					       const struct sctp_association *asoc)
 {
 	struct sctp_chunk auth;
 
-	if (!chunk->auth_chunk)
-		return !sctp_auth_recv_cid(chunk->chunk_hdr->type, asoc);
+	if (!chunk->auth_chunk) {
+		if (sctp_auth_recv_cid(chunk->chunk_hdr->type, asoc))
+			return SCTP_IERROR_BAD_SIG;
+		return SCTP_IERROR_NO_ERROR;
+	}
 
 	/* SCTP-AUTH:  auth_chunk pointer is only set when the cookie-echo
 	 * is supposed to be authenticated and we have to do delayed
@@ -654,7 +658,7 @@ static bool sctp_auth_chunk_verify(struct net *net, struct sctp_chunk *chunk,
 
 	/* Make sure that we and the peer are AUTH capable */
 	if (!net->sctp.auth_enable || !asoc->peer.auth_capable)
-		return false;
+		return SCTP_IERROR_BAD_SIG;
 
 	/* set-up our fake chunk so that we can process it */
 	auth.skb = chunk->auth_chunk;
@@ -666,7 +670,7 @@ static bool sctp_auth_chunk_verify(struct net *net, struct sctp_chunk *chunk,
 	skb_pull(chunk->auth_chunk, sizeof(struct sctp_chunkhdr));
 	auth.transport = chunk->transport;
 
-	return sctp_sf_authenticate(asoc, &auth) == SCTP_IERROR_NO_ERROR;
+	return sctp_sf_authenticate(asoc, &auth);
 }
 
 /*
@@ -826,8 +830,11 @@ enum sctp_disposition sctp_sf_do_5_1D_ce(struct net *net,
 	if (error)
 		goto nomem_init;
 
-	if (!sctp_auth_chunk_verify(net, chunk, new_asoc)) {
+	error = sctp_auth_chunk_verify(net, chunk, new_asoc);
+	if (error != SCTP_IERROR_NO_ERROR) {
 		sctp_association_free(new_asoc);
+		if (error == SCTP_IERROR_NOMEM)
+			return SCTP_DISPOSITION_NOMEM;
 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 	}
 
@@ -1889,6 +1896,7 @@ static enum sctp_disposition sctp_sf_do_dupcook_a(
 {
 	struct sctp_init_chunk *peer_init;
 	enum sctp_disposition disposition;
+	enum sctp_ierror error;
 	struct sctp_ulpevent *ev;
 	struct sctp_chunk *repl;
 	struct sctp_chunk *err;
@@ -1904,8 +1912,12 @@ static enum sctp_disposition sctp_sf_do_dupcook_a(
 	if (sctp_auth_asoc_init_active_key(new_asoc, GFP_ATOMIC))
 		goto nomem;
 
-	if (!sctp_auth_chunk_verify(net, chunk, new_asoc))
+	error = sctp_auth_chunk_verify(net, chunk, new_asoc);
+	if (error != SCTP_IERROR_NO_ERROR) {
+		if (error == SCTP_IERROR_NOMEM)
+			return SCTP_DISPOSITION_NOMEM;
 		return SCTP_DISPOSITION_DISCARD;
+	}
 
 	/* Make sure no new addresses are being added during the
 	 * restart.  Though this is a pretty complicated attack
@@ -2011,6 +2023,7 @@ static enum sctp_disposition sctp_sf_do_dupcook_b(
 					struct sctp_association *new_asoc)
 {
 	struct sctp_init_chunk *peer_init;
+	enum sctp_ierror error;
 	struct sctp_chunk *repl;
 
 	/* new_asoc is a brand-new association, so these are not yet
@@ -2024,8 +2037,12 @@ static enum sctp_disposition sctp_sf_do_dupcook_b(
 	if (sctp_auth_asoc_init_active_key(new_asoc, GFP_ATOMIC))
 		goto nomem;
 
-	if (!sctp_auth_chunk_verify(net, chunk, new_asoc))
+	error = sctp_auth_chunk_verify(net, chunk, new_asoc);
+	if (error != SCTP_IERROR_NO_ERROR) {
+		if (error == SCTP_IERROR_NOMEM)
+			return SCTP_DISPOSITION_NOMEM;
 		return SCTP_DISPOSITION_DISCARD;
+	}
 
 	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
 			SCTP_STATE(SCTP_STATE_ESTABLISHED));
@@ -2118,6 +2135,7 @@ static enum sctp_disposition sctp_sf_do_dupcook_d(
 					struct sctp_association *new_asoc)
 {
 	struct sctp_ulpevent *ev = NULL, *ai_ev = NULL, *auth_ev = NULL;
+	enum sctp_ierror error;
 	struct sctp_chunk *repl;
 
 	/* Clarification from Implementor's Guide:
@@ -2127,8 +2145,12 @@ static enum sctp_disposition sctp_sf_do_dupcook_d(
 	 * a COOKIE ACK.
 	 */
 
-	if (!sctp_auth_chunk_verify(net, chunk, asoc))
+	error = sctp_auth_chunk_verify(net, chunk, asoc);
+	if (error != SCTP_IERROR_NO_ERROR) {
+		if (error == SCTP_IERROR_NOMEM)
+			return SCTP_DISPOSITION_NOMEM;
 		return SCTP_DISPOSITION_DISCARD;
+	}
 
 	/* Don't accidentally move back into established state. */
 	if (asoc->state < SCTP_STATE_ESTABLISHED) {
@@ -4455,9 +4477,12 @@ static enum sctp_ierror sctp_sf_authenticate(
 
 	memset(digest, 0, sig_len);
 
-	sctp_auth_calculate_hmac(asoc, chunk->skb,
-				 (struct sctp_auth_chunk *)chunk->chunk_hdr,
-				 sh_key, GFP_ATOMIC);
+	if (sctp_auth_calculate_hmac(asoc, chunk->skb,
+				     (struct sctp_auth_chunk *)chunk->chunk_hdr,
+				     sh_key, GFP_ATOMIC)) {
+		kfree(save_digest);
+		return SCTP_IERROR_NOMEM;
+	}
 
 	/* Discard the packet if the digests do not match */
 	if (crypto_memneq(save_digest, digest, sig_len)) {

gemini-3.1-pro-preview

null

null

							input: 5346
							output: 20
							thoughts: 428
						

**Analyzing the SCTP Authentication HMAC Patch**

Okay, so we've got a patch here that's changing the way the HMAC calculation is handled in SCTP authentication. Specifically, they've gone from a `void` return type in `sctp_auth_calculate_hmac` to an `int`, to allow for the handling of memory allocation failures with the `-ENOMEM` error code. This is definitely a good change; robust error handling is crucial, especially in a core networking function like authentication. The callers seem to be properly updated to manage these errors and propagate them appropriately, returning `SCTP_IERROR_NOMEM` or `SCTP_DISPOSITION_NOMEM`.

The immediate thought is: is this functional and fuzz-worthy? Absolutely, yes. Memory allocation failures in authentication are a legitimate and important failure scenario to test. This is a functional change to the SCTP authentication, which is definitely reachable.

Now, let's identify the key symbols we should focus on for fuzzing. We have `sctp_auth_calculate_hmac` itself, which is the immediate target. Then there's `sctp_packet_pack` (which is static, so let's see if it's inlined - otherwise, maybe skip it, focusing on API entrypoints or state machine functions). We have `sctp_packet_transmit`, `sctp_auth_chunk_verify` (which is also static), and then a bunch of state machine functions, `sctp_sf_do_5_1D_ce`, `sctp_sf_do_dupcook_a`, `sctp_sf_do_dupcook_b`, `sctp_sf_do_dupcook_d`, and `sctp_sf_authenticate`.

The key entrypoints to include for fuzzing should be: `sctp_auth_calculate_hmac`, `sctp_packet_transmit`, and then those state machine functions that are involved in authentication: `sctp_sf_do_5_1D_ce`, `sctp_sf_do_dupcook_a`, `sctp_sf_do_dupcook_b`, `sctp_sf_do_dupcook_d`, and `sctp_sf_authenticate`.

Just a quick check now, make sure SCTP is even enabled. `IP_SCTP` in Kconfig, got it. Let's verify that's all set up correctly.

{
  "Expression": "config IP_SCTP"
}

{
  "Output": "net/sctp/Kconfig-5-\nnet/sctp/Kconfig:6:menuconfig IP_SCTP\nnet/sctp/Kconfig-7-\ttristate \"The SCTP Protocol\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 6409
							output: 19
							thoughts: 15
						

Here's my attempt at summarizing the thought process, tailored for an expert audience:

**Investigating SCTP Authentication Configurations**

Okay, so I'm digging into SCTP authentication, and I'm wondering if there are any specific configuration parameters I need to pay close attention to. This isn't just a generic security assessment; I'm looking for the nitty-gritty details. Are there any SCTP-specific settings that relate to the authentication process itself? Things that might not be immediately obvious from a general security posture review. I need to know if I'm missing something, or if there is something I can exploit.

no matches

{
  "Expression": "config SCTP_AUTH"
}

{
  "error": "no matches"
}

gemini-3.1-pro-preview

null

null

							input: 6590
							output: 29
							thoughts: 18
						

Here's my thought process, summarized as if I were considering this issue:

**Delving into System Parameters**

Okay, hold on a second. I was just looking at that `net->sctp.auth_enable` setting... and a lightbulb just went off. That's not some obscure kernel variable, that's a *sysctl*. Meaning I can tune it at runtime without needing a full reboot or even a module reload. That changes everything, or at least it changes my approach! I need to really understand the implications of toggling that. Is it a persistent change, or is it only effective until the next reboot? What's the recommended way to modify it? I should check the kernel documentation for `sysctl` and SCTP authentication to get a precise understanding before making any decisions. Now I need to review what effects this is intended to have. Good thing I just had that thought, before diving into something far more involved.

{
  "Expression": "auth_enable",
  "PathPrefix": "net/sctp/"
}

{
  "Output": "net/sctp/auth.c=722=int sctp_auth_set_key(struct sctp_endpoint *ep,\n--\nnet/sctp/auth.c-738-\t} else {\nnet/sctp/auth.c:739:\t\tif (!ep-\u003eauth_enable)\nnet/sctp/auth.c-740-\t\t\treturn -EACCES;\n--\nnet/sctp/auth.c=785=int sctp_auth_set_active_key(struct sctp_endpoint *ep,\n--\nnet/sctp/auth.c-798-\t} else {\nnet/sctp/auth.c:799:\t\tif (!ep-\u003eauth_enable)\nnet/sctp/auth.c-800-\t\t\treturn -EACCES;\n--\nnet/sctp/auth.c=828=int sctp_auth_del_key_id(struct sctp_endpoint *ep,\n--\nnet/sctp/auth.c-846-\t} else {\nnet/sctp/auth.c:847:\t\tif (!ep-\u003eauth_enable)\nnet/sctp/auth.c-848-\t\t\treturn -EACCES;\n--\nnet/sctp/auth.c=872=int sctp_auth_deact_key_id(struct sctp_endpoint *ep,\n--\nnet/sctp/auth.c-889-\t} else {\nnet/sctp/auth.c:890:\t\tif (!ep-\u003eauth_enable)\nnet/sctp/auth.c-891-\t\t\treturn -EACCES;\n--\nnet/sctp/endpointola.c=50=static struct sctp_endpoint *sctp_endpoint_init(struct sctp_endpoint *ep,\n--\nnet/sctp/endpointola.c-57-\tep-\u003easconf_enable = net-\u003esctp.addip_enable;\nnet/sctp/endpointola.c:58:\tep-\u003eauth_enable = net-\u003esctp.auth_enable;\nnet/sctp/endpointola.c:59:\tif (ep-\u003eauth_enable) {\nnet/sctp/endpointola.c-60-\t\tif (sctp_auth_init(ep, gfp))\n--\nnet/sctp/protocol.c=1289=static int __net_init sctp_defaults_init(struct net *net)\n--\nnet/sctp/protocol.c-1314-\t/* Whether cookie authentication is enabled(1) or not(0) */\nnet/sctp/protocol.c:1315:\tnet-\u003esctp.cookie_auth_enable =\nnet/sctp/protocol.c-1316-\t\t!IS_ENABLED(CONFIG_SCTP_DEFAULT_COOKIE_HMAC_NONE);\n--\nnet/sctp/protocol.c-1361-\t/* Disable AUTH by default. */\nnet/sctp/protocol.c:1362:\tnet-\u003esctp.auth_enable = 0;\nnet/sctp/protocol.c-1363-\n--\nnet/sctp/sm_make_chunk.c=198=struct sctp_chunk *sctp_make_init(const struct sctp_association *asoc,\n--\nnet/sctp/sm_make_chunk.c-272-\t/* Account for AUTH related parameters */\nnet/sctp/sm_make_chunk.c:273:\tif (ep-\u003eauth_enable) {\nnet/sctp/sm_make_chunk.c-274-\t\t/* Add random parameter length*/\n--\nnet/sctp/sm_make_chunk.c-355-\t/* Add SCTP-AUTH chunks to the parameter list */\nnet/sctp/sm_make_chunk.c:356:\tif (ep-\u003eauth_enable) {\nnet/sctp/sm_make_chunk.c-357-\t\tsctp_addto_chunk(retval, sizeof(asoc-\u003ec.auth_random),\n--\nnet/sctp/sm_make_chunk.c=1645=static struct sctp_cookie_param *sctp_pack_cookie(\n--\nnet/sctp/sm_make_chunk.c-1711-\t/* Sign the cookie, if cookie authentication is enabled. */\nnet/sctp/sm_make_chunk.c:1712:\tif (sctp_sk(ep-\u003ebase.sk)-\u003ecookie_auth_enable) {\nnet/sctp/sm_make_chunk.c-1713-\t\tstatic_assert(sizeof(cookie-\u003emac) == SHA256_DIGEST_SIZE);\n--\nnet/sctp/sm_make_chunk.c=1722=struct sctp_association *sctp_unpack_cookie(\n--\nnet/sctp/sm_make_chunk.c-1774-\t/* Verify the cookie's MAC, if cookie authentication is enabled. */\nnet/sctp/sm_make_chunk.c:1775:\tif (sctp_sk(ep-\u003ebase.sk)-\u003ecookie_auth_enable) {\nnet/sctp/sm_make_chunk.c-1776-\t\tu8 mac[SHA256_DIGEST_SIZE];\n--\nnet/sctp/sm_make_chunk.c=2031=static void sctp_process_ext_param(struct sctp_association *asoc,\n--\nnet/sctp/sm_make_chunk.c-2050-\t\t\t */\nnet/sctp/sm_make_chunk.c:2051:\t\t\tif (asoc-\u003eep-\u003eauth_enable)\nnet/sctp/sm_make_chunk.c-2052-\t\t\t\tasoc-\u003epeer.auth_capable = 1;\n--\nnet/sctp/sm_make_chunk.c=2147=static enum sctp_ierror sctp_verify_param(struct net *net,\n--\nnet/sctp/sm_make_chunk.c-2211-\tcase SCTP_PARAM_RANDOM:\nnet/sctp/sm_make_chunk.c:2212:\t\tif (!ep-\u003eauth_enable)\nnet/sctp/sm_make_chunk.c-2213-\t\t\tgoto unhandled;\n--\nnet/sctp/sm_make_chunk.c-2228-\tcase SCTP_PARAM_CHUNKS:\nnet/sctp/sm_make_chunk.c:2229:\t\tif (!ep-\u003eauth_enable)\nnet/sctp/sm_make_chunk.c-2230-\t\t\tgoto unhandled;\n--\nnet/sctp/sm_make_chunk.c-2244-\tcase SCTP_PARAM_HMAC_ALGO:\nnet/sctp/sm_make_chunk.c:2245:\t\tif (!ep-\u003eauth_enable)\nnet/sctp/sm_make_chunk.c-2246-\t\t\tgoto unhandled;\n--\nnet/sctp/sm_make_chunk.c=2532=static int sctp_process_param(struct sctp_association *asoc,\n--\nnet/sctp/sm_make_chunk.c-2690-\tcase SCTP_PARAM_RANDOM:\nnet/sctp/sm_make_chunk.c:2691:\t\tif (!ep-\u003eauth_enable)\nnet/sctp/sm_make_chunk.c-2692-\t\t\tgoto fall_through;\n--\nnet/sctp/sm_make_chunk.c-2704-\tcase SCTP_PARAM_HMAC_ALGO:\nnet/sctp/sm_make_chunk.c:2705:\t\tif (!ep-\u003eauth_enable)\nnet/sctp/sm_make_chunk.c-2706-\t\t\tgoto fall_through;\n--\nnet/sctp/sm_make_chunk.c-2721-\tcase SCTP_PARAM_CHUNKS:\nnet/sctp/sm_make_chunk.c:2722:\t\tif (!ep-\u003eauth_enable)\nnet/sctp/sm_make_chunk.c-2723-\t\t\tgoto fall_through;\n--\nnet/sctp/sm_statefuns.c=640=static enum sctp_ierror sctp_auth_chunk_verify(struct net *net,\n--\nnet/sctp/sm_statefuns.c-659-\t/* Make sure that we and the peer are AUTH capable */\nnet/sctp/sm_statefuns.c:660:\tif (!net-\u003esctp.auth_enable || !asoc-\u003epeer.auth_capable)\nnet/sctp/sm_statefuns.c-661-\t\treturn SCTP_IERROR_BAD_SIG;\n--\nnet/sctp/sm_statefuns.c=707=enum sctp_disposition sctp_sf_do_5_1D_ce(struct net *net,\n--\nnet/sctp/sm_statefuns.c-795-\tcid = peer_init-\u003echunk_hdr.type;\nnet/sctp/sm_statefuns.c:796:\tif (!sctp_sk(sk)-\u003ecookie_auth_enable \u0026\u0026\nnet/sctp/sm_statefuns.c-797-\t    !sctp_verify_init(net, ep, asoc, cid, peer_init, chunk,\n--\nnet/sctp/sm_statefuns.c=2246=enum sctp_disposition sctp_sf_do_5_2_4_dupcook(\n--\nnet/sctp/sm_statefuns.c-2330-\t\tcid = peer_init-\u003echunk_hdr.type;\nnet/sctp/sm_statefuns.c:2331:\t\tif (!sctp_sk(ep-\u003ebase.sk)-\u003ecookie_auth_enable \u0026\u0026\nnet/sctp/sm_statefuns.c-2332-\t\t    !sctp_verify_init(net, ep, asoc, cid, peer_init, chunk,\n--\nnet/sctp/socket.c=3579=static int sctp_setsockopt_auth_chunk(struct sock *sk,\n--\nnet/sctp/socket.c-3584-\nnet/sctp/socket.c:3585:\tif (!ep-\u003eauth_enable)\nnet/sctp/socket.c-3586-\t\treturn -EACCES;\n--\nnet/sctp/socket.c=3609=static int sctp_setsockopt_hmac_ident(struct sock *sk,\n--\nnet/sctp/socket.c-3615-\nnet/sctp/socket.c:3616:\tif (!ep-\u003eauth_enable)\nnet/sctp/socket.c-3617-\t\treturn -EACCES;\n--\nnet/sctp/socket.c=4341=static int sctp_setsockopt_asconf_supported(struct sock *sk,\n--\nnet/sctp/socket.c-4359-\nnet/sctp/socket.c:4360:\tif (ep-\u003easconf_enable \u0026\u0026 ep-\u003eauth_enable) {\nnet/sctp/socket.c-4361-\t\tsctp_auth_ep_add_chunkid(ep, SCTP_CID_ASCONF);\n--\nnet/sctp/socket.c=4371=static int sctp_setsockopt_auth_supported(struct sock *sk,\n--\nnet/sctp/socket.c-4397-\nnet/sctp/socket.c:4398:\tep-\u003eauth_enable = !!params-\u003eassoc_value;\nnet/sctp/socket.c-4399-\tretval = 0;\n--\nnet/sctp/socket.c=5021=static int sctp_init_sock(struct sock *sk)\n--\nnet/sctp/socket.c-5055-\nnet/sctp/socket.c:5056:\tsp-\u003ecookie_auth_enable = net-\u003esctp.cookie_auth_enable;\nnet/sctp/socket.c-5057-\n--\nnet/sctp/socket.c=6960=static int sctp_getsockopt_hmac_ident(struct sock *sk, int len,\n--\nnet/sctp/socket.c-6969-\nnet/sctp/socket.c:6970:\tif (!ep-\u003eauth_enable)\nnet/sctp/socket.c-6971-\t\treturn -EACCES;\n--\nnet/sctp/socket.c=6996=static int sctp_getsockopt_active_key(struct sock *sk, int len,\n--\nnet/sctp/socket.c-7018-\t} else {\nnet/sctp/socket.c:7019:\t\tif (!ep-\u003eauth_enable)\nnet/sctp/socket.c-7020-\t\t\treturn -EACCES;\n--\nnet/sctp/socket.c=7076=static int sctp_getsockopt_local_auth_chunks(struct sock *sk, int len,\n--\nnet/sctp/socket.c-7103-\t} else {\nnet/sctp/socket.c:7104:\t\tif (!ep-\u003eauth_enable)\nnet/sctp/socket.c-7105-\t\t\treturn -EACCES;\n--\nnet/sctp/socket.c=7895=static int sctp_getsockopt_auth_supported(struct sock *sk, int len,\n--\nnet/sctp/socket.c-7919-\tparams.assoc_value = asoc ? asoc-\u003epeer.auth_capable\nnet/sctp/socket.c:7920:\t\t\t\t  : sctp_sk(sk)-\u003eep-\u003eauth_enable;\nnet/sctp/socket.c-7921-\n--\nnet/sctp/sysctl.c=95=static struct ctl_table sctp_net_table[] = {\n--\nnet/sctp/sysctl.c-176-\t\t.procname\t= \"cookie_hmac_alg\",\nnet/sctp/sysctl.c:177:\t\t.data\t\t= \u0026init_net.sctp.cookie_auth_enable,\nnet/sctp/sysctl.c-178-\t\t.maxlen\t\t= 8,\n--\nnet/sctp/sysctl.c-264-\t{\nnet/sctp/sysctl.c:265:\t\t.procname\t= \"addip_noauth_enable\",\nnet/sctp/sysctl.c-266-\t\t.data\t\t= \u0026init_net.sctp.addip_noauth,\n--\nnet/sctp/sysctl.c-285-\t{\nnet/sctp/sysctl.c:286:\t\t.procname\t= \"auth_enable\",\nnet/sctp/sysctl.c:287:\t\t.data\t\t= \u0026init_net.sctp.auth_enable,\nnet/sctp/sysctl.c-288-\t\t.maxlen\t\t= sizeof(int),\n--\nnet/sctp/sysctl.c=387=static int proc_sctp_do_hmac_alg(const struct ctl_table *ctl, int write,\n--\nnet/sctp/sysctl.c-390-\tstruct net *net = container_of(ctl-\u003edata, struct net,\nnet/sctp/sysctl.c:391:\t\t\t\t       sctp.cookie_auth_enable);\nnet/sctp/sysctl.c-392-\tstruct ctl_table tbl;\n--\nnet/sctp/sysctl.c-404-\t\tif (!strcmp(tmp, \"sha256\")) {\nnet/sctp/sysctl.c:405:\t\t\tnet-\u003esctp.cookie_auth_enable = 1;\nnet/sctp/sysctl.c-406-\t\t\treturn 0;\n--\nnet/sctp/sysctl.c-408-\t\tif (!strcmp(tmp, \"none\")) {\nnet/sctp/sysctl.c:409:\t\t\tnet-\u003esctp.cookie_auth_enable = 0;\nnet/sctp/sysctl.c-410-\t\t\treturn 0;\n--\nnet/sctp/sysctl.c-413-\t}\nnet/sctp/sysctl.c:414:\tif (net-\u003esctp.cookie_auth_enable)\nnet/sctp/sysctl.c-415-\t\ttbl.data = (char *)\"sha256\";\n--\nnet/sctp/sysctl.c=488=static int proc_sctp_do_auth(const struct ctl_table *ctl, int write,\n--\nnet/sctp/sysctl.c-490-{\nnet/sctp/sysctl.c:491:\tstruct net *net = container_of(ctl-\u003edata, struct net, sctp.auth_enable);\nnet/sctp/sysctl.c-492-\tstruct ctl_table tbl;\n--\nnet/sctp/sysctl.c-500-\telse\nnet/sctp/sysctl.c:501:\t\ttbl.data = \u0026net-\u003esctp.auth_enable;\nnet/sctp/sysctl.c-502-\n--\nnet/sctp/sysctl.c-506-\nnet/sctp/sysctl.c:507:\t\tnet-\u003esctp.auth_enable = new_value;\nnet/sctp/sysctl.c-508-\t\t/* Update the value in the control socket */\nnet/sctp/sysctl.c-509-\t\tlock_sock(sk);\nnet/sctp/sysctl.c:510:\t\tsctp_sk(sk)-\u003eep-\u003eauth_enable = new_value;\nnet/sctp/sysctl.c-511-\t\trelease_sock(sk);\n"
}

gemini-3.1-pro-preview

null

null

							input: 11467
							output: 26
							thoughts: 71
						

**Navigating the SCTP Configuration Labyrinth**

Okay, so I'm looking at this `auth_enable` thing, and it's flagged as a `sysctl`, not a Kconfig option. Interesting. It's making me double-check the configuration paths. The main SCTP flag, `IP_SCTP`, that's Kconfig. Now I'm starting to wonder if there are *other* configurations buried in here. It always pays to be thorough. I'm going to jump into `net/sctp/Kconfig` specifically and see if I can find `SCTP_DEFAULT_COOKIE_HMAC_NONE`. I want to make sure I haven't missed a related, potentially impactful, setting. Gotta map out the landscape.

{
  "Expression": "config SCTP_DEFAULT_COOKIE_HMAC_NONE"
}

{
  "Output": "net/sctp/Kconfig=62=config SCTP_DEFAULT_COOKIE_HMAC_SHA256\n--\nnet/sctp/Kconfig-64-\nnet/sctp/Kconfig:65:config SCTP_DEFAULT_COOKIE_HMAC_NONE\nnet/sctp/Kconfig-66-\tbool \"None\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 11827
							output: 35
							thoughts: 16
						

Okay, let's dive into this. Here's my take on those thoughts, as if they're my own:

**Analyzing the SCTP Kconfig Configuration**

Alright, I'm thinking, "Time to get a good look at the entire `net/sctp/Kconfig` file." Given my understanding of networking and the Linux kernel, this `Kconfig` file is going to be the central control point for configuring Stream Control Transmission Protocol (SCTP) features and modules during the kernel build process. I'm going to be looking for several key things. I want to see how the various SCTP options are laid out hierarchically, the dependencies between them, and how they relate to other networking subsystems within the kernel. I'll be focused on how it's structured, its organization, the different configuration symbols, their default values, and the associated help text. I anticipate finding conditionals based on architecture, kernel version, or other dependencies like whether other networking protocols are enabled. I'll be looking for things like: how options for bundled support such as M3UA or over IPsec are handled, the configuration options for features such as multiple streams, and how these settings are exposed in the build system. This `Kconfig` file will provide the ultimate map of how SCTP is enabled, customized, and integrated into a specific Linux kernel build. Understanding this file is paramount to any effective kernel-level SCTP development and tuning.

{
  "File": "net/sctp/Kconfig",
  "FirstLine": 1,
  "LineCount": 100
}

{
  "Contents": "   1:\t# SPDX-License-Identifier: GPL-2.0-only\n   2:\t#\n   3:\t# SCTP configuration\n   4:\t#\n   5:\t\n   6:\tmenuconfig IP_SCTP\n   7:\t\ttristate \"The SCTP Protocol\"\n   8:\t\tdepends on INET\n   9:\t\tselect CRYPTO_LIB_SHA1\n  10:\t\tselect CRYPTO_LIB_SHA256\n  11:\t\tselect CRYPTO_LIB_UTILS\n  12:\t\tselect NET_CRC32C\n  13:\t\tselect NET_UDP_TUNNEL\n  14:\t\thelp\n  15:\t\t  Stream Control Transmission Protocol\n  16:\t\n  17:\t\t  From RFC 2960 \u003chttp://www.ietf.org/rfc/rfc2960.txt\u003e.\n  18:\t\n  19:\t\t  \"SCTP is a reliable transport protocol operating on top of a\n  20:\t\t  connectionless packet network such as IP.  It offers the following\n  21:\t\t  services to its users:\n  22:\t\n  23:\t\t  -- acknowledged error-free non-duplicated transfer of user data,\n  24:\t\t  -- data fragmentation to conform to discovered path MTU size,\n  25:\t\t  -- sequenced delivery of user messages within multiple streams,\n  26:\t\t  with an option for order-of-arrival delivery of individual user\n  27:\t\t  messages,\n  28:\t\t  -- optional bundling of multiple user messages into a single SCTP\n  29:\t\t  packet, and\n  30:\t\t  -- network-level fault tolerance through supporting of multi-\n  31:\t\t  homing at either or both ends of an association.\"\n  32:\t\n  33:\t\t  To compile this protocol support as a module, choose M here: the\n  34:\t\t  module will be called sctp. Debug messages are handled by the\n  35:\t\t  kernel's dynamic debugging framework.\n  36:\t\n  37:\t\t  If in doubt, say N.\n  38:\t\n  39:\tif IP_SCTP\n  40:\t\n  41:\tconfig SCTP_DBG_OBJCNT\n  42:\t\tbool \"SCTP: Debug object counts\"\n  43:\t\tdepends on PROC_FS\n  44:\t\thelp\n  45:\t\t  If you say Y, this will enable debugging support for counting the\n  46:\t\t  type of objects that are currently allocated.  This is useful for\n  47:\t\t  identifying memory leaks. This debug information can be viewed by\n  48:\t\t  'cat /proc/net/sctp/sctp_dbg_objcnt'\n  49:\t\n  50:\t\t  If unsure, say N\n  51:\t\n  52:\tchoice\n  53:\t\tprompt \"Default SCTP cookie authentication method\"\n  54:\t\tdefault SCTP_DEFAULT_COOKIE_HMAC_SHA256\n  55:\t\thelp\n  56:\t\t  This option sets the default SCTP cookie authentication method, for\n  57:\t\t  when a method hasn't been explicitly selected via the\n  58:\t\t  net.sctp.cookie_hmac_alg sysctl.\n  59:\t\n  60:\t\t  If unsure, choose the default (HMAC-SHA256).\n  61:\t\n  62:\tconfig SCTP_DEFAULT_COOKIE_HMAC_SHA256\n  63:\t\tbool \"HMAC-SHA256\"\n  64:\t\n  65:\tconfig SCTP_DEFAULT_COOKIE_HMAC_NONE\n  66:\t\tbool \"None\"\n  67:\t\n  68:\tendchoice\n  69:\t\n  70:\tconfig INET_SCTP_DIAG\n  71:\t\tdepends on INET_DIAG\n  72:\t\tdef_tristate INET_DIAG\n  73:\t\n  74:\t\n  75:\tendif # IP_SCTP\n"
}

gemini-3.1-pro-preview

null

null

							input: 13181
							output: 33
							thoughts: 375
						

**My Assessment of the SCTP Configuration**

Right, it looks like `IP_SCTP` is the only configuration option we need to consider here. Now, let's carefully review the focus symbols identified. I'm seeing:

*   `sctp_auth_calculate_hmac`
*   `sctp_packet_transmit`
*   `sctp_sf_do_5_1D_ce`
*   `sctp_sf_do_dupcook_a`
*   `sctp_sf_do_dupcook_b`
*   `sctp_sf_do_dupcook_d`
*   `sctp_sf_authenticate`

These all look relevant, but I need to quickly re-evaluate `sctp_packet_transmit`. It seemed a bit broad at first, but remembering the error handling flow, the actual error handling resides within a static function `sctp_packet_pack` and, critically, `sctp_packet_transmit` calls this function. So, I will include it.

Now, let's verify that the authentication-related symbols are actually static as I initially thought. I need to make sure I'm not overlooking something.

Okay, checking `net/sctp/sm_statefuns.c`, `sctp_auth_chunk_verify` *is* indeed static. Its callers are `sctp_sf_do_5_1D_ce`, `sctp_sf_do_dupcook_a`, `sctp_sf_do_dupcook_b`, and `sctp_sf_do_dupcook_d`. That confirms my initial assessment.

Now to re-verify `sctp_sf_authenticate`. Yes, it's also static, in `net/sctp/sm_statefuns.c`. I need to ensure there are no surprises here.

{
  "Expression": "sctp_sf_authenticate",
  "PathPrefix": "net/sctp/"
}

{
  "Output": "net/sctp/sm_statefuns.c=142=static enum sctp_disposition sctp_sf_violation_chunk(\n--\nnet/sctp/sm_statefuns.c-149-\nnet/sctp/sm_statefuns.c:150:static enum sctp_ierror sctp_sf_authenticate(\nnet/sctp/sm_statefuns.c-151-\t\t\t\t\tconst struct sctp_association *asoc,\n--\nnet/sctp/sm_statefuns.c=640=static enum sctp_ierror sctp_auth_chunk_verify(struct net *net,\n--\nnet/sctp/sm_statefuns.c-672-\nnet/sctp/sm_statefuns.c:673:\treturn sctp_sf_authenticate(asoc, \u0026auth);\nnet/sctp/sm_statefuns.c-674-}\n--\nnet/sctp/sm_statefuns.c=4335=enum sctp_disposition sctp_sf_eat_fwd_tsn_fast(\n--\nnet/sctp/sm_statefuns.c-4422- */\nnet/sctp/sm_statefuns.c:4423:static enum sctp_ierror sctp_sf_authenticate(\nnet/sctp/sm_statefuns.c-4424-\t\t\t\t\tconst struct sctp_association *asoc,\n--\nnet/sctp/sm_statefuns.c=4501=enum sctp_disposition sctp_sf_eat_auth(struct net *net,\n--\nnet/sctp/sm_statefuns.c-4527-\tauth_hdr = (struct sctp_authhdr *)chunk-\u003eskb-\u003edata;\nnet/sctp/sm_statefuns.c:4528:\terror = sctp_sf_authenticate(asoc, chunk);\nnet/sctp/sm_statefuns.c-4529-\tswitch (error) {\n"
}

gemini-3.1-pro-preview

null

null

							input: 14562
							output: 35
							thoughts: 117
						

Okay, let's break this down. **Analyzing the `sctp_sf_authenticate` Function**

Right, so `sctp_sf_authenticate` is defined as a static function, which is interesting. Now, I need to understand who is calling this specific function. From what I can see, `sctp_sf_eat_auth`, `sctp_sf_do_5_1D_ce`, `sctp_sf_do_dupcook_a`, `sctp_sf_do_dupcook_b`, and `sctp_sf_do_dupcook_d` are all calling it.

Hang on a second… I could have sworn that `sctp_sf_eat_auth` was static too. I should double check that because my memory might not be the best and this is important.

{
  "Expression": "sctp_sf_eat_auth",
  "PathPrefix": "net/sctp/"
}

{
  "Output": "net/sctp/sm_statefuns.c=4423=static enum sctp_ierror sctp_sf_authenticate(\n--\nnet/sctp/sm_statefuns.c-4500-\nnet/sctp/sm_statefuns.c:4501:enum sctp_disposition sctp_sf_eat_auth(struct net *net,\nnet/sctp/sm_statefuns.c-4502-\t\t\t\t       const struct sctp_endpoint *ep,\n--\nnet/sctp/sm_statetable.c=498=reconf_chunk_event_table[SCTP_NUM_RECONF_CHUNK_TYPES][SCTP_STATE_NUM_STATES] = {\n--\nnet/sctp/sm_statetable.c-507-\t/* SCTP_STATE_COOKIE_ECHOED */ \\\nnet/sctp/sm_statetable.c:508:\tTYPE_SCTP_FUNC(sctp_sf_eat_auth), \\\nnet/sctp/sm_statetable.c-509-\t/* SCTP_STATE_ESTABLISHED */ \\\nnet/sctp/sm_statetable.c:510:\tTYPE_SCTP_FUNC(sctp_sf_eat_auth), \\\nnet/sctp/sm_statetable.c-511-\t/* SCTP_STATE_SHUTDOWN_PENDING */ \\\nnet/sctp/sm_statetable.c:512:\tTYPE_SCTP_FUNC(sctp_sf_eat_auth), \\\nnet/sctp/sm_statetable.c-513-\t/* SCTP_STATE_SHUTDOWN_SENT */ \\\nnet/sctp/sm_statetable.c:514:\tTYPE_SCTP_FUNC(sctp_sf_eat_auth), \\\nnet/sctp/sm_statetable.c-515-\t/* SCTP_STATE_SHUTDOWN_RECEIVED */ \\\nnet/sctp/sm_statetable.c:516:\tTYPE_SCTP_FUNC(sctp_sf_eat_auth), \\\nnet/sctp/sm_statetable.c-517-\t/* SCTP_STATE_SHUTDOWN_ACK_SENT */ \\\nnet/sctp/sm_statetable.c:518:\tTYPE_SCTP_FUNC(sctp_sf_eat_auth), \\\nnet/sctp/sm_statetable.c-519-} /* TYPE_SCTP_AUTH */\n"
}

gemini-3.1-pro-preview

null

null

							input: 15550
							output: 38
							thoughts: 97
						

**Analyzing SCTP Function Attributes**

Okay, so I'm looking over this SCTP code, specifically at these functions. It's good to clarify these details. I can see that `sctp_sf_eat_auth` is definitely not declared as static – that's something I need to keep in mind. And I confirm that `sctp_sf_do_5_1D_ce` is also non-static, which is what I expected. Now, I have a feeling about the `sctp_sf_do_dupcook_*` family. Let's see... are `sctp_sf_do_dupcook_a`, `sctp_sf_do_dupcook_b`, and `sctp_sf_do_dupcook_d` declared static? Gotta double check those to be sure, and I'll make sure to note that in my working document.

{
  "Expression": "sctp_sf_do_dupcook_",
  "PathPrefix": "net/sctp/"
}

{
  "Output": "net/sctp/sm_statefuns.c=1860=static int sctp_sf_do_assoc_update(struct sctp_association *asoc,\n--\nnet/sctp/sm_statefuns.c-1888- */\nnet/sctp/sm_statefuns.c:1889:static enum sctp_disposition sctp_sf_do_dupcook_a(\nnet/sctp/sm_statefuns.c-1890-\t\t\t\t\tstruct net *net,\n--\nnet/sctp/sm_statefuns.c-2016-/* This case represents an initialization collision.  */\nnet/sctp/sm_statefuns.c:2017:static enum sctp_disposition sctp_sf_do_dupcook_b(\nnet/sctp/sm_statefuns.c-2018-\t\t\t\t\tstruct net *net,\n--\nnet/sctp/sm_statefuns.c-2105-/* This case represents an initialization collision.  */\nnet/sctp/sm_statefuns.c:2106:static enum sctp_disposition sctp_sf_do_dupcook_c(\nnet/sctp/sm_statefuns.c-2107-\t\t\t\t\tstruct net *net,\n--\nnet/sctp/sm_statefuns.c-2128-/* This case represents an initialization collision.  */\nnet/sctp/sm_statefuns.c:2129:static enum sctp_disposition sctp_sf_do_dupcook_d(\nnet/sctp/sm_statefuns.c-2130-\t\t\t\t\tstruct net *net,\n--\nnet/sctp/sm_statefuns.c=2246=enum sctp_disposition sctp_sf_do_5_2_4_dupcook(\n--\nnet/sctp/sm_statefuns.c-2354-\tcase 'A': /* Association restart. */\nnet/sctp/sm_statefuns.c:2355:\t\tretval = sctp_sf_do_dupcook_a(net, ep, asoc, chunk, commands,\nnet/sctp/sm_statefuns.c-2356-\t\t\t\t\t      new_asoc);\n--\nnet/sctp/sm_statefuns.c-2359-\tcase 'B': /* Collision case B. */\nnet/sctp/sm_statefuns.c:2360:\t\tretval = sctp_sf_do_dupcook_b(net, ep, asoc, chunk, commands,\nnet/sctp/sm_statefuns.c-2361-\t\t\t\t\t      new_asoc);\n--\nnet/sctp/sm_statefuns.c-2364-\tcase 'C': /* Collision case C. */\nnet/sctp/sm_statefuns.c:2365:\t\tretval = sctp_sf_do_dupcook_c(net, ep, asoc, chunk, commands,\nnet/sctp/sm_statefuns.c-2366-\t\t\t\t\t      new_asoc);\n--\nnet/sctp/sm_statefuns.c-2369-\tcase 'D': /* Collision case D. */\nnet/sctp/sm_statefuns.c:2370:\t\tretval = sctp_sf_do_dupcook_d(net, ep, asoc, chunk, commands,\nnet/sctp/sm_statefuns.c-2371-\t\t\t\t\t      new_asoc);\n"
}

gemini-3.1-pro-preview

null

null

							input: 16812
							output: 36
							thoughts: 139
						

**Analyzing Potential Static Functions**

Alright, the functions I'm examining seem to be statically declared. My next step is to pinpoint the non-static function that's calling them, which appears to be `sctp_sf_do_5_2_4_dupcook`. Based on this, I need to focus my investigation on a select group of symbols related to this.

The crucial ones to examine are:
-   `sctp_auth_calculate_hmac`
-   `sctp_packet_transmit`
-   `sctp_sf_do_5_1D_ce`
-   `sctp_sf_do_5_2_4_dupcook`
-   `sctp_sf_eat_auth`

Now, I'll need to confirm whether `sctp_auth_calculate_hmac` is, in fact, non-static. This is the starting point for digging further.

{
  "Expression": "sctp_auth_calculate_hmac",
  "PathPrefix": "net/sctp/"
}

{
  "Output": "net/sctp/auth.c=595=int sctp_auth_recv_cid(enum sctp_cid chunk, const struct sctp_association *asoc)\n--\nnet/sctp/auth.c-615- */\nnet/sctp/auth.c:616:int sctp_auth_calculate_hmac(const struct sctp_association *asoc,\nnet/sctp/auth.c-617-\t\t\t     struct sk_buff *skb, struct sctp_auth_chunk *auth,\n--\nnet/sctp/output.c=436=static int sctp_packet_pack(struct sctp_packet *packet,\n--\nnet/sctp/output.c-519-\t\tif (auth) {\nnet/sctp/output.c:520:\t\t\tif (sctp_auth_calculate_hmac(tp-\u003easoc, nskb, auth,\nnet/sctp/output.c-521-\t\t\t\t\t\t     packet-\u003eauth-\u003eshkey, gfp)) {\n--\nnet/sctp/sm_statefuns.c=4423=static enum sctp_ierror sctp_sf_authenticate(\n--\nnet/sctp/sm_statefuns.c-4479-\nnet/sctp/sm_statefuns.c:4480:\tif (sctp_auth_calculate_hmac(asoc, chunk-\u003eskb,\nnet/sctp/sm_statefuns.c-4481-\t\t\t\t     (struct sctp_auth_chunk *)chunk-\u003echunk_hdr,\n"
}

gemini-3.1-pro-preview

null

null

							input: 17615
							output: 196
							thoughts: 332
						

**My Assessment of the SCTP Authentication Patch**

Okay, so this isn't static code, that's clear. My initial scan of the code points me to these key symbols for deeper analysis: `sctp_auth_calculate_hmac`, `sctp_packet_transmit`, `sctp_sf_do_5_1D_ce`, `sctp_sf_do_5_2_4_dupcook`, and `sctp_sf_eat_auth`. I'm seeing the `IP_SCTP` config being relevant.

Let's quickly verify that `IP_SCTP` is the only config of relevance here. Hm, I need to make sure I'm not missing anything else that might come into play. Ah, alright. Looks like `IP_SCTP` also selects `CRYPTO_LIB_SHA1`, `CRYPTO_LIB_SHA256`, and `CRYPTO_LIB_UTILS`. So, yes, `IP_SCTP` should be sufficient.

Now, let's look at the functional impact. The patch is about handling memory allocation failures in `sctp_auth_calculate_hmac`. This is a functional change, not just a cosmetic one. From what I understand, the patch changes the return type of `sctp_auth_calculate_hmac` and then modifies the calls to that function in `sctp_packet_pack` and `sctp_sf_authenticate` to handle an error. This prevents the possibility of a null pointer dereference or silent failures. This type of core network logic change has potential vulnerability.

Therefore, this is definitely something I want to fuzz. It's a functional change in a critical area.

Time to call `set-results`.

{
  "EnableConfigs": [
    "IP_SCTP"
  ],
  "FocusSymbols": [
    "sctp_auth_calculate_hmac",
    "sctp_packet_transmit",
    "sctp_sf_do_5_1D_ce",
    "sctp_sf_do_5_2_4_dupcook",
    "sctp_sf_eat_auth"
  ],
  "Reasoning": "The patch modifies SCTP authentication HMAC calculation to properly handle and propagate memory allocation failures (-ENOMEM). It updates the return type of sctp_auth_calculate_hmac and modifies callers in sctp_packet_pack and sctp_sf_authenticate to handle the error, preventing potential null pointer dereferences or silent failures. This is a functional change in core networking logic that should be fuzzed.",
  "WorthFuzzing": true
}

{
  "EnableConfigs": [
    "IP_SCTP"
  ],
  "FocusSymbols": [
    "sctp_auth_calculate_hmac",
    "sctp_packet_transmit",
    "sctp_sf_do_5_1D_ce",
    "sctp_sf_do_5_2_4_dupcook",
    "sctp_sf_eat_auth"
  ],
  "Reasoning": "The patch modifies SCTP authentication HMAC calculation to properly handle and propagate memory allocation failures (-ENOMEM). It updates the return type of sctp_auth_calculate_hmac and modifies callers in sctp_packet_pack and sctp_sf_authenticate to handle the error, preventing potential null pointer dereferences or silent failures. This is a functional change in core networking logic that should be fuzzed.",
  "WorthFuzzing": true
}