AI Trajectory

null

{
  "EnableConfigs": [
    "UDF_FS"
  ],
  "FocusSymbols": [
    "udf_expand_file_adinicb"
  ],
  "Reasoning": "The patch modifies `udf_expand_file_adinicb` in the UDF filesystem to allocate the block underlying the data using `udf_map_block`. This function is reachable via standard filesystem operations like write and truncate on UDF filesystems.",
  "WorthFuzzing": true
}

null

{
  "PatchDiff": "commit aae39f9894824444206ff6c8660ddf9b79830fa8\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Thu Jul 30 21:48:14 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/fs/udf/inode.c b/fs/udf/inode.c\nindex 68c6c2ba8ed1a..ef06642cf75c4 100644\n--- a/fs/udf/inode.c\n+++ b/fs/udf/inode.c\n@@ -343,6 +343,10 @@ int udf_expand_file_adinicb(struct inode *inode)\n {\n \tstruct folio *folio;\n \tstruct udf_inode_info *iinfo = UDF_I(inode);\n+\tstruct udf_map_rq map = {\n+\t\t.lblk = 0,\n+\t\t.iflags = UDF_MAP_CREATE,\n+\t};\n \tint err;\n \n \tWARN_ON_ONCE(!inode_is_locked(inode));\n@@ -372,20 +376,27 @@ int udf_expand_file_adinicb(struct inode *inode)\n \t\tiinfo-\u003ei_alloc_type = ICBTAG_FLAG_AD_SHORT;\n \telse\n \t\tiinfo-\u003ei_alloc_type = ICBTAG_FLAG_AD_LONG;\n+\tup_write(\u0026iinfo-\u003ei_data_sem);\n+\n+\t/* Allocate the block underlying the data */\n+\terr = udf_map_block(inode, \u0026map);\n+\tif (err \u003c 0)\n+\t\tgoto restore;\n+\n \tfolio_mark_dirty(folio);\n \tfolio_unlock(folio);\n-\tup_write(\u0026iinfo-\u003ei_data_sem);\n \terr = filemap_fdatawrite(inode-\u003ei_mapping);\n \tif (err) {\n \t\t/* Restore everything back so that we don't lose data... */\n \t\tfolio_lock(folio);\n+restore:\n \t\tdown_write(\u0026iinfo-\u003ei_data_sem);\n \t\tmemcpy_from_folio(iinfo-\u003ei_data + iinfo-\u003ei_lenEAttr,\n \t\t\t\tfolio, 0, inode-\u003ei_size);\n-\t\tfolio_unlock(folio);\n \t\tiinfo-\u003ei_alloc_type = ICBTAG_FLAG_AD_IN_ICB;\n \t\tiinfo-\u003ei_lenAlloc = inode-\u003ei_size;\n \t\tup_write(\u0026iinfo-\u003ei_data_sem);\n+\t\tfolio_unlock(folio);\n \t}\n \tfolio_put(folio);\n \tmark_inode_dirty(inode);\n"
}

best-expensive

null

{
  "EnableConfigs": [
    "UDF_FS"
  ],
  "FocusSymbols": [
    "udf_expand_file_adinicb"
  ],
  "Reasoning": "The patch modifies `udf_expand_file_adinicb` in the UDF filesystem to allocate the block underlying the data using `udf_map_block`. This function is reachable via standard filesystem operations like write and truncate on UDF filesystems.",
  "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 aae39f9894824444206ff6c8660ddf9b79830fa8
Author: syz-cluster <triage@syzkaller.com>
Date:   Thu Jul 30 21:48:14 2026 +0000

    syz-cluster: applied patch under review

diff --git a/fs/udf/inode.c b/fs/udf/inode.c
index 68c6c2ba8ed1a..ef06642cf75c4 100644
--- a/fs/udf/inode.c
+++ b/fs/udf/inode.c
@@ -343,6 +343,10 @@ int udf_expand_file_adinicb(struct inode *inode)
 {
 	struct folio *folio;
 	struct udf_inode_info *iinfo = UDF_I(inode);
+	struct udf_map_rq map = {
+		.lblk = 0,
+		.iflags = UDF_MAP_CREATE,
+	};
 	int err;
 
 	WARN_ON_ONCE(!inode_is_locked(inode));
@@ -372,20 +376,27 @@ int udf_expand_file_adinicb(struct inode *inode)
 		iinfo->i_alloc_type = ICBTAG_FLAG_AD_SHORT;
 	else
 		iinfo->i_alloc_type = ICBTAG_FLAG_AD_LONG;
+	up_write(&iinfo->i_data_sem);
+
+	/* Allocate the block underlying the data */
+	err = udf_map_block(inode, &map);
+	if (err < 0)
+		goto restore;
+
 	folio_mark_dirty(folio);
 	folio_unlock(folio);
-	up_write(&iinfo->i_data_sem);
 	err = filemap_fdatawrite(inode->i_mapping);
 	if (err) {
 		/* Restore everything back so that we don't lose data... */
 		folio_lock(folio);
+restore:
 		down_write(&iinfo->i_data_sem);
 		memcpy_from_folio(iinfo->i_data + iinfo->i_lenEAttr,
 				folio, 0, inode->i_size);
-		folio_unlock(folio);
 		iinfo->i_alloc_type = ICBTAG_FLAG_AD_IN_ICB;
 		iinfo->i_lenAlloc = inode->i_size;
 		up_write(&iinfo->i_data_sem);
+		folio_unlock(folio);
 	}
 	folio_put(folio);
 	mark_inode_dirty(inode);

gemini-3.1-pro-preview

null

null

							input: 2438
							output: 24
							thoughts: 143
						

**Analyzing the UDF Filesystem Patch**

Okay, so I've got this patch for the UDF filesystem, specifically in `fs/udf/inode.c`. Looks like it's touching the `udf_expand_file_adinicb` function. My initial impression is that the changes relate to how the filesystem handles allocating blocks for file data. The patch introduces a call to `udf_map_block(inode, &map)`, which I'm guessing is responsible for actually grabbing the disk space. If that call fails, it cleverly rolls back to the `restore` label, which is important to see, so I'll keep an eye on that.

The other bit that catches my eye are the locking modifications, specifically the interactions around `folio_unlock(folio)` and `up_write(&iinfo->i_data_sem)`. These are classic areas where concurrency issues can rear their heads, so I'll want to understand *why* those lines are being changed. It's likely related to the block allocation process, ensuring that data structures are synchronized correctly during the expansion of the file.

Now, to get a better grip on the full impact of these changes, I need to understand where `udf_expand_file_adinicb` is called from. I'll use `grepper` or whatever search tool is most efficient, to pinpoint all the call sites. That will give me the broader context and help me evaluate the correctness and potential performance implications of this patch more thoroughly.

{
  "Expression": "udf_expand_file_adinicb"
}

{
  "Output": "fs/udf/file.c=89=static ssize_t udf_file_write_iter(struct kiocb *iocb, struct iov_iter *from)\n--\nfs/udf/file.c-105-\t\tfilemap_invalidate_lock(inode-\u003ei_mapping);\nfs/udf/file.c:106:\t\tretval = udf_expand_file_adinicb(inode);\nfs/udf/file.c-107-\t\tfilemap_invalidate_unlock(inode-\u003ei_mapping);\n--\nfs/udf/inode.c=324=const struct address_space_operations udf_aops = {\n--\nfs/udf/inode.c-341- */\nfs/udf/inode.c:342:int udf_expand_file_adinicb(struct inode *inode)\nfs/udf/inode.c-343-{\n--\nfs/udf/inode.c=1280=int udf_setsize(struct inode *inode, loff_t newsize)\n--\nfs/udf/inode.c-1299-\t\t\t}\nfs/udf/inode.c:1300:\t\t\terr = udf_expand_file_adinicb(inode);\nfs/udf/inode.c-1301-\t\t\tif (err)\n--\nfs/udf/udfdecl.h=149=static inline struct inode *udf_iget(struct super_block *sb,\n--\nfs/udf/udfdecl.h-153-}\nfs/udf/udfdecl.h:154:extern int udf_expand_file_adinicb(struct inode *);\nfs/udf/udfdecl.h-155-extern struct buffer_head *udf_bread(struct inode *inode, udf_pblk_t block,\n"
}

gemini-3.1-pro-preview

null

null

							input: 3382
							output: 19
							thoughts: 102
						

**UDF Filesystem Vulnerability Research**

Okay, so I've spotted `udf_expand_file_adinicb` and it's being called from both `udf_file_write_iter` and `udf_setsize`. That immediately flags a potential issue, especially since both of those are standard operations within a filesystem. Write and truncate, classic filesystem functionality. That strongly suggests this function is directly reachable via normal UDF filesystem interactions. Thinking logically, since UDF *is* a filesystem, fuzzing it is definitely on the table.

Now, I need to confirm the build configuration. I'm assuming `UDF_FS` is required for this to be present in the kernel, but let's quickly double-check `fs/udf/Kconfig` to rule out any other hidden dependencies. I want to be certain I have the complete picture before diving in. Need to know all the angles here.

{
  "Expression": "config UDF_FS"
}

{
  "Output": "fs/udf/Kconfig-1-# SPDX-License-Identifier: GPL-2.0-only\nfs/udf/Kconfig:2:config UDF_FS\nfs/udf/Kconfig-3-\ttristate \"UDF file system support\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 3775
							output: 36
							thoughts: 37
						

Okay, here's my take on those thoughts, framed as an expert's internal monologue:

**Analyzing the UDF Filesystem Configuration**

Right, so the configuration in question is `UDF_FS`. Okay, that's clear enough. Now, I need to get to the heart of how this thing expands a file. My first stop should definitely be the core functionality related to UDF file expansion. Specifically, I need to understand how the UDF filesystem handles adding new blocks to an existing file, and how it manages the ADINICB structure during that expansion process. That likely lives somewhere in `fs/udf/inode.c`. Let's dig into `udf_expand_file_adinicb` and see what the code has to teach me. Hopefully, it's well-commented... because that's what I really need to get my teeth into.

{
  "File": "fs/udf/inode.c",
  "FirstLine": 342,
  "LineCount": 50
}

{
  "Contents": " 342:\tint udf_expand_file_adinicb(struct inode *inode)\n 343:\t{\n 344:\t\tstruct folio *folio;\n 345:\t\tstruct udf_inode_info *iinfo = UDF_I(inode);\n 346:\t\tstruct udf_map_rq map = {\n 347:\t\t\t.lblk = 0,\n 348:\t\t\t.iflags = UDF_MAP_CREATE,\n 349:\t\t};\n 350:\t\tint err;\n 351:\t\n 352:\t\tWARN_ON_ONCE(!inode_is_locked(inode));\n 353:\t\tif (!iinfo-\u003ei_lenAlloc) {\n 354:\t\t\tdown_write(\u0026iinfo-\u003ei_data_sem);\n 355:\t\t\tif (UDF_QUERY_FLAG(inode-\u003ei_sb, UDF_FLAG_USE_SHORT_AD))\n 356:\t\t\t\tiinfo-\u003ei_alloc_type = ICBTAG_FLAG_AD_SHORT;\n 357:\t\t\telse\n 358:\t\t\t\tiinfo-\u003ei_alloc_type = ICBTAG_FLAG_AD_LONG;\n 359:\t\t\tup_write(\u0026iinfo-\u003ei_data_sem);\n 360:\t\t\tmark_inode_dirty(inode);\n 361:\t\t\treturn 0;\n 362:\t\t}\n 363:\t\n 364:\t\tfolio = __filemap_get_folio(inode-\u003ei_mapping, 0,\n 365:\t\t\t\tFGP_LOCK | FGP_ACCESSED | FGP_CREAT, GFP_KERNEL);\n 366:\t\tif (IS_ERR(folio))\n 367:\t\t\treturn PTR_ERR(folio);\n 368:\t\n 369:\t\tif (!folio_test_uptodate(folio))\n 370:\t\t\tudf_adinicb_read_folio(folio);\n 371:\t\tdown_write(\u0026iinfo-\u003ei_data_sem);\n 372:\t\tmemset(iinfo-\u003ei_data + iinfo-\u003ei_lenEAttr, 0x00,\n 373:\t\t       iinfo-\u003ei_lenAlloc);\n 374:\t\tiinfo-\u003ei_lenAlloc = 0;\n 375:\t\tif (UDF_QUERY_FLAG(inode-\u003ei_sb, UDF_FLAG_USE_SHORT_AD))\n 376:\t\t\tiinfo-\u003ei_alloc_type = ICBTAG_FLAG_AD_SHORT;\n 377:\t\telse\n 378:\t\t\tiinfo-\u003ei_alloc_type = ICBTAG_FLAG_AD_LONG;\n 379:\t\tup_write(\u0026iinfo-\u003ei_data_sem);\n 380:\t\n 381:\t\t/* Allocate the block underlying the data */\n 382:\t\terr = udf_map_block(inode, \u0026map);\n 383:\t\tif (err \u003c 0)\n 384:\t\t\tgoto restore;\n 385:\t\n 386:\t\tfolio_mark_dirty(folio);\n 387:\t\tfolio_unlock(folio);\n 388:\t\terr = filemap_fdatawrite(inode-\u003ei_mapping);\n 389:\t\tif (err) {\n 390:\t\t\t/* Restore everything back so that we don't lose data... */\n 391:\t\t\tfolio_lock(folio);\n"
}

gemini-3.1-pro-preview

null

null

							input: 4899
							output: 103
							thoughts: 124
						

**Analyzing the UDF Filesystem Patch**

Okay, so this patch introduces `udf_map_block`, which seems to be the function that actually handles allocating the block where the data resides. I can confirm that it's functional and reachable, which is a good starting point. Now, the main symbol I need to focus on is `udf_expand_file_adinicb`.

My next step is to quickly verify whether `udf_expand_file_adinicb` is static or not. Knowing this will help understand its scope and potential impact on the system. Ah, it's not static. It's exported in `fs/udf/udfdecl.h` and actively used in `fs/udf/file.c`. This means it has a wider scope than just this particular module, and its behavior could have broader implications.

Given this understanding, I'm confident in setting WorthFuzzing to true.

{
  "EnableConfigs": [
    "UDF_FS"
  ],
  "FocusSymbols": [
    "udf_expand_file_adinicb"
  ],
  "Reasoning": "The patch modifies `udf_expand_file_adinicb` in the UDF filesystem to allocate the block underlying the data using `udf_map_block`. This function is reachable via standard filesystem operations like write and truncate on UDF filesystems.",
  "WorthFuzzing": true
}

{
  "EnableConfigs": [
    "UDF_FS"
  ],
  "FocusSymbols": [
    "udf_expand_file_adinicb"
  ],
  "Reasoning": "The patch modifies `udf_expand_file_adinicb` in the UDF filesystem to allocate the block underlying the data using `udf_map_block`. This function is reachable via standard filesystem operations like write and truncate on UDF filesystems.",
  "WorthFuzzing": true
}