AI Trajectory

null

{
  "EnableConfigs": [
    "NTFS_FS"
  ],
  "FocusSymbols": [
    "ntfs_file_write_iter",
    "ntfs_filemap_page_mkwrite"
  ],
  "Reasoning": "The patch adds functional checks to prevent writing to the $MFT file via direct file writes or memory-mapped writes in the NTFS driver. This modifies reachable core logic for the NTFS filesystem and should be fuzzed to ensure the checks correctly prevent unauthorized access without causing regressions.",
  "WorthFuzzing": true
}

null

{
  "PatchDiff": "commit d46b93c9f98e548b0b77b2cbbf269b8406444f32\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Thu Jul 2 12:11:05 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/fs/ntfs/file.c b/fs/ntfs/file.c\nindex 6a7b638e523d91..0d8f11e5ccb78a 100644\n--- a/fs/ntfs/file.c\n+++ b/fs/ntfs/file.c\n@@ -550,6 +550,12 @@ static ssize_t ntfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)\n \tif (NVolShutdown(vol))\n \t\treturn -EIO;\n \n+\tif (ni-\u003emft_no == FILE_MFT) {\n+\t\tntfs_error(vi-\u003ei_sb, \"Attempt to write to $MFT denied (mft_no: 0x%lx)\",\n+\t\t\t\tni-\u003emft_no);\n+\t\treturn -EACCES;\n+\t}\n+\n \tif (NInoEncrypted(ni)) {\n \t\tntfs_error(vi-\u003ei_sb, \"Writing for %s files is not supported yet\",\n \t\t\t   NInoCompressed(ni) ? \"Compressed\" : \"Encrypted\");\n@@ -618,8 +624,15 @@ static ssize_t ntfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)\n static vm_fault_t ntfs_filemap_page_mkwrite(struct vm_fault *vmf)\n {\n \tstruct inode *inode = file_inode(vmf-\u003evma-\u003evm_file);\n+\tstruct ntfs_inode *ni = NTFS_I(inode);\n \tvm_fault_t ret;\n \n+\tif (ni-\u003emft_no == FILE_MFT) {\n+\t\tntfs_error(inode-\u003ei_sb, \"Attempt to write to $MFT via mmap denied (mft_no: 0x%lx)\",\n+\t\t\t\tni-\u003emft_no);\n+\t\treturn VM_FAULT_SIGBUS;\n+\t}\n+\n \tsb_start_pagefault(inode-\u003ei_sb);\n \tfile_update_time(vmf-\u003evma-\u003evm_file);\n \n"
}

gemini-3.1-pro-preview

null

{
  "EnableConfigs": [
    "NTFS_FS"
  ],
  "FocusSymbols": [
    "ntfs_file_write_iter",
    "ntfs_filemap_page_mkwrite"
  ],
  "Reasoning": "The patch adds functional checks to prevent writing to the $MFT file via direct file writes or memory-mapped writes in the NTFS driver. This modifies reachable core logic for the NTFS filesystem and should be fuzzed to ensure the checks correctly prevent unauthorized access without causing regressions.",
  "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).

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.
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.
   Do not list too generic configs (we already have them enabled). Only list those that
   specifically cover the modified code. 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 d46b93c9f98e548b0b77b2cbbf269b8406444f32
Author: syz-cluster <triage@syzkaller.com>
Date:   Thu Jul 2 12:11:05 2026 +0000

    syz-cluster: applied patch under review

diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c
index 6a7b638e523d91..0d8f11e5ccb78a 100644
--- a/fs/ntfs/file.c
+++ b/fs/ntfs/file.c
@@ -550,6 +550,12 @@ static ssize_t ntfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	if (NVolShutdown(vol))
 		return -EIO;
 
+	if (ni->mft_no == FILE_MFT) {
+		ntfs_error(vi->i_sb, "Attempt to write to $MFT denied (mft_no: 0x%lx)",
+				ni->mft_no);
+		return -EACCES;
+	}
+
 	if (NInoEncrypted(ni)) {
 		ntfs_error(vi->i_sb, "Writing for %s files is not supported yet",
 			   NInoCompressed(ni) ? "Compressed" : "Encrypted");
@@ -618,8 +624,15 @@ static ssize_t ntfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 static vm_fault_t ntfs_filemap_page_mkwrite(struct vm_fault *vmf)
 {
 	struct inode *inode = file_inode(vmf->vma->vm_file);
+	struct ntfs_inode *ni = NTFS_I(inode);
 	vm_fault_t ret;
 
+	if (ni->mft_no == FILE_MFT) {
+		ntfs_error(inode->i_sb, "Attempt to write to $MFT via mmap denied (mft_no: 0x%lx)",
+				ni->mft_no);
+		return VM_FAULT_SIGBUS;
+	}
+
 	sb_start_pagefault(inode->i_sb);
 	file_update_time(vmf->vma->vm_file);
 

gemini-3.1-pro-preview

null

null

							input: 2157
							output: 31
							thoughts: 126
						

**Analyzing the NTFS Write Protection Patch**

Okay, so I'm looking at this patch targeting `fs/ntfs/file.c`. It seems they're implementing write protection for the `$MFT` file within the NTFS filesystem. The core idea is to prevent any modifications to the Master File Table. From what I see, they've added checks within `ntfs_file_write_iter` and `ntfs_filemap_page_mkwrite`. Specifically, it appears the code is verifying if `ni->mft_no` matches `FILE_MFT`. If it does, indicating we're dealing with the `$MFT`, the patch returns either `-EACCES` (permission denied) or `VM_FAULT_SIGBUS`. This makes sense; direct modification of the `$MFT` could corrupt the entire filesystem.

Now, I want to confirm a few things. First, I'll quickly glance over `fs/ntfs/file.c` to see the exact context of these new checks. I’ll look for any potential edge cases that were missed or any dependencies that need further analysis. Then, I need to check `fs/ntfs/Kconfig` to refresh my memory on the configuration options for NTFS. I want to be certain this protection is enabled by default or at least configurable, and to see if there are any specific kernel configurations that might impact the effectiveness or behavior of this change. It would be a problem if this new code conflicted with anything else, so reviewing the configuration is critical. Overall, this seems like a solid, necessary addition to maintain file system integrity.

{
  "Expression": "config NTFS_FS",
  "PathPrefix": "fs/ntfs/Kconfig"
}

{
  "Output": "fs/ntfs/Kconfig-1-# SPDX-License-Identifier: GPL-2.0-only\nfs/ntfs/Kconfig:2:config NTFS_FS\nfs/ntfs/Kconfig-3-\ttristate \"NTFS file system support\"\n--\nfs/ntfs/Kconfig=13=config NTFS_DEBUG\n--\nfs/ntfs/Kconfig-34-\nfs/ntfs/Kconfig:35:config NTFS_FS_POSIX_ACL\nfs/ntfs/Kconfig-36-\tbool \"NTFS POSIX Access Control Lists\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 2799
							output: 31
							thoughts: 36
						

Okay, here's my interpretation of those thoughts, presented as my own mental process:

**Diving into the NTFS Configuration**

Alright, the system's indicating it's using the `NTFS_FS` configuration. But hold on a second... is that *all* of it? There's a nagging feeling, a flicker of memory... wasn't there also a `NTFS_RW` option kicking around? Let me quickly cross-reference that. I need to be sure I understand the full configuration scope. Okay, better get over to `fs/ntfs/Kconfig` to refresh my memory and verify the dependencies and implications of these settings. Let's make sure I'm not missing anything critical in the build process.

no matches

{
  "Expression": "config NTFS_RW",
  "PathPrefix": "fs/ntfs/Kconfig"
}

{
  "error": "no matches"
}

gemini-3.1-pro-preview

null

null

							input: 3037
							output: 30
							thoughts: 29
						

Okay, here's my interpretation of that thought process, assuming I'm an expert in file systems and kernel configuration:

**Navigating the NTFS Configuration Landscape**

Right, so I need to check something related to read/write support for NTFS. The most logical place to start is the kernel configuration file related to the NTFS filesystem itself. That would be `fs/ntfs/Kconfig`. I'll want to verify the existence, state, and dependencies of the read-write options. Specifically, I'm thinking about the options named `NTFS_RW` and `NTFS_FS_RW`. Are they defined? Are they enabled? What other settings influence them? This is the usual spot to look for the fundamental controls that determine if the NTFS driver includes read-write capabilities. Time to open that file and get to the bottom of this.

{
  "Expression": "config NTFS_",
  "PathPrefix": "fs/ntfs/Kconfig"
}

{
  "Output": "fs/ntfs/Kconfig-1-# SPDX-License-Identifier: GPL-2.0-only\nfs/ntfs/Kconfig:2:config NTFS_FS\nfs/ntfs/Kconfig-3-\ttristate \"NTFS file system support\"\n--\nfs/ntfs/Kconfig-12-\nfs/ntfs/Kconfig:13:config NTFS_DEBUG\nfs/ntfs/Kconfig-14-\tbool \"NTFS debugging support\"\n--\nfs/ntfs/Kconfig-34-\nfs/ntfs/Kconfig:35:config NTFS_FS_POSIX_ACL\nfs/ntfs/Kconfig-36-\tbool \"NTFS POSIX Access Control Lists\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 3454
							output: 29
							thoughts: 26
						

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

**Initial Reaction to NTFS_RW Removal**

Okay, hold on a second... `NTFS_RW` is *gone*? That's a significant change. I need to get to the bottom of this immediately. My first instinct is to dive straight into the source. I'm going to pull up the `fs/ntfs/Kconfig` file and pore over it completely. I need to understand *why* this change was made. Was it a performance decision? Security vulnerability? Is it a permanent removal or a temporary disable? What are the implications for users who rely on read-write NTFS support? Time to roll up my sleeves and dissect the configuration options. This will require a thorough examination.

{
  "Expression": "config NTFS",
  "PathPrefix": "fs/ntfs/Kconfig"
}

{
  "Output": "fs/ntfs/Kconfig-1-# SPDX-License-Identifier: GPL-2.0-only\nfs/ntfs/Kconfig:2:config NTFS_FS\nfs/ntfs/Kconfig-3-\ttristate \"NTFS file system support\"\n--\nfs/ntfs/Kconfig-12-\nfs/ntfs/Kconfig:13:config NTFS_DEBUG\nfs/ntfs/Kconfig-14-\tbool \"NTFS debugging support\"\n--\nfs/ntfs/Kconfig-34-\nfs/ntfs/Kconfig:35:config NTFS_FS_POSIX_ACL\nfs/ntfs/Kconfig-36-\tbool \"NTFS POSIX Access Control Lists\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 3852
							output: 34
							thoughts: 13
						

Okay, let's dive into this. Here's my take on that `fs/ntfs/Kconfig` file, as I understand it:

**NTFS Configuration - Decoding the Kconfig**

Alright, I'm going to take a look at the `fs/ntfs/Kconfig` file. I'm already expecting it to outline the various configuration options related to the NTFS filesystem driver within the kernel. Given my expertise, I'm focusing on how it presents the options, their dependencies, and any subtle implications for performance or security. I'm anticipating finding the usual suspects: support for read/write access, extended attributes, perhaps even journal recovery options. My goal is to see how the developers have balanced functionality with potential resource constraints. I'll be particularly interested in whether there are any conditional dependencies on other kernel subsystems or features. Finally, I'll be looking for clues regarding any changes or improvements made to the driver over the history of this configuration file. I want to see if they're addressing any previous weaknesses or problems.

{
  "File": "fs/ntfs/Kconfig",
  "FirstLine": 1,
  "LineCount": 100
}

{
  "Contents": "   1:\t# SPDX-License-Identifier: GPL-2.0-only\n   2:\tconfig NTFS_FS\n   3:\t\ttristate \"NTFS file system support\"\n   4:\t\tselect NLS\n   5:\t\tselect FS_IOMAP\n   6:\t\thelp\n   7:\t\t  NTFS is the file system of Microsoft Windows NT, 2000, XP and 2003.\n   8:\t\t  This allows you to mount devices formatted with the ntfs file system.\n   9:\t\n  10:\t\t  To compile this as a module, choose M here: the module will be called\n  11:\t\t  ntfs.\n  12:\t\n  13:\tconfig NTFS_DEBUG\n  14:\t\tbool \"NTFS debugging support\"\n  15:\t\tdepends on NTFS_FS\n  16:\t\thelp\n  17:\t\t  If you are experiencing any problems with the NTFS file system, say\n  18:\t\t  Y here.  This will result in additional consistency checks to be\n  19:\t\t  performed by the driver as well as additional debugging messages to\n  20:\t\t  be written to the system log.  Note that debugging messages are\n  21:\t\t  disabled by default.  To enable them, supply the option debug_msgs=1\n  22:\t\t  at the kernel command line when booting the kernel or as an option\n  23:\t\t  to insmod when loading the ntfs module.  Once the driver is active,\n  24:\t\t  you can enable debugging messages by doing (as root):\n  25:\t\t  echo 1 \u003e /proc/sys/fs/ntfs-debug\n  26:\t\t  Replacing the \"1\" with \"0\" would disable debug messages.\n  27:\t\n  28:\t\t  If you leave debugging messages disabled, this results in little\n  29:\t\t  overhead, but enabling debug messages results in very significant\n  30:\t\t  slowdown of the system.\n  31:\t\n  32:\t\t  When reporting bugs, please try to have available a full dump of\n  33:\t\t  debugging messages while the misbehaviour was occurring.\n  34:\t\n  35:\tconfig NTFS_FS_POSIX_ACL\n  36:\t\tbool \"NTFS POSIX Access Control Lists\"\n  37:\t\tdepends on NTFS_FS\n  38:\t\tselect FS_POSIX_ACL\n  39:\t\thelp\n  40:\t\t  POSIX Access Control Lists (ACLs) support additional access rights\n  41:\t\t  for users and groups beyond the standard owner/group/world scheme.\n  42:\t\n  43:\t\t  This option enables ACL support for ntfs, providing functional parity\n  44:\t\t  with ntfs3 drivier.\n  45:\t\n  46:\t\t  NOTE: this is linux only feature. Windows will ignore these ACLs.\n  47:\t\n  48:\t\t  If you don't know what Access Control Lists are, say N.\n"
}

gemini-3.1-pro-preview

null

null

							input: 4839
							output: 36
							thoughts: 51
						

Okay, let's see... **Investigating a Removed Feature**

Hmm, so `NTFS_RW` is no longer in `fs/ntfs/Kconfig`. That's interesting. I wonder what the implications are. My first instinct, given my experience, is to immediately check the actual implementation. Specifically, if `ntfs_file_write_iter` is still compiled. I'll need to look at `fs/ntfs/file.c` to understand if this write operation is still present in the code, even without the associated Kconfig option. Knowing this helps me determine the impact of this removal, whether it's simply disabling a feature, or if it has ramifications for other code that might depend on this function. Time to dive into the source!

{
  "Expression": "ntfs_file_write_iter",
  "PathPrefix": "fs/ntfs/file.c"
}

{
  "Output": "fs/ntfs/file.c=495=static ssize_t ntfs_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)\n--\nfs/ntfs/file.c-537-\nfs/ntfs/file.c:538:static ssize_t ntfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)\nfs/ntfs/file.c-539-{\n--\nfs/ntfs/file.c=1159=const struct file_operations ntfs_file_ops = {\n--\nfs/ntfs/file.c-1161-\t.read_iter\t= ntfs_file_read_iter,\nfs/ntfs/file.c:1162:\t.write_iter\t= ntfs_file_write_iter,\nfs/ntfs/file.c-1163-\t.fsync\t\t= ntfs_file_fsync,\n"
}

gemini-3.1-pro-preview

null

null

							input: 5340
							output: 32
							thoughts: 87
						

**NTFS Driver Confusion**

Okay, hold on a second. I need to clarify something about the NTFS drivers. Is `fs/ntfs` the legacy driver, or is that the new, improved one? Right, the new one is definitely `fs/ntfs3`. So that makes `fs/ntfs` the older one. But I'm remembering something about `fs/ntfs` having `NTFS_RW` at some point. Did they eventually get rid of that define and just make it always read-write? I can't quite recall. The easiest way to confirm this is to just go check the `fs/ntfs/Makefile`, it's all in there. Time to dig in and confirm what's what.

{
  "File": "fs/ntfs/Makefile",
  "FirstLine": 1,
  "LineCount": 20
}

{
  "Contents": "   1:\t# SPDX-License-Identifier: GPL-2.0\n   2:\t\n   3:\tobj-$(CONFIG_NTFS_FS) += ntfs.o\n   4:\t\n   5:\tntfs-y := aops.o attrib.o collate.o dir.o file.o index.o inode.o \\\n   6:\t\t  mft.o mst.o namei.o runlist.o super.o unistr.o attrlist.o ea.o \\\n   7:\t\t  upcase.o bitmap.o lcnalloc.o logfile.o reparse.o compress.o \\\n   8:\t\t  iomap.o debug.o sysctl.o object_id.o bdev-io.o\n   9:\t\n  10:\tccflags-$(CONFIG_NTFS_DEBUG) += -DDEBUG\n"
}

gemini-3.1-pro-preview

null

null

							input: 5833
							output: 115
							thoughts: 440
						

**Fuzzing the NTFS Driver: Write Operations**

Okay, so this patch is modifying the `fs/ntfs/file.c` file, specifically the `ntfs_file_write_iter` and `ntfs_filemap_page_mkwrite` functions, which means it's touching the old NTFS driver. This is definitely something I need to fuzz. It's a functional change, so it's a prime target for testing.

My focus should be on `ntfs_file_write_iter` – that's the NTFS write iterator – and `ntfs_filemap_page_mkwrite`, which handles page faults during mmap writes. I have to make sure writes, both direct and memory-mapped, are handled correctly, especially around the core checks.

Looking at the configs, I see it only needs `NTFS_FS`, so that's simple enough.

Re-examining the patch, there's a critical check in there preventing writes to the `$MFT` file through either method. This protection is key, and it's essential that I fuzz this to ensure the checks work and don't introduce regressions. The patch now checks for the MFT number and rejects writes.

So, here's the plan. My focus symbols are definitely `ntfs_file_write_iter` and `ntfs_filemap_page_mkwrite`. The configuration is just `NTFS_FS`. This is all about verifying that the `$MFT` write protection works. Now, let's call `set-results`.

{
  "EnableConfigs": [
    "NTFS_FS"
  ],
  "FocusSymbols": [
    "ntfs_file_write_iter",
    "ntfs_filemap_page_mkwrite"
  ],
  "Reasoning": "The patch adds functional checks to prevent writing to the $MFT file via direct file writes or memory-mapped writes in the NTFS driver. This modifies reachable core logic for the NTFS filesystem and should be fuzzed to ensure the checks correctly prevent unauthorized access without causing regressions.",
  "WorthFuzzing": true
}

{
  "EnableConfigs": [
    "NTFS_FS"
  ],
  "FocusSymbols": [
    "ntfs_file_write_iter",
    "ntfs_filemap_page_mkwrite"
  ],
  "Reasoning": "The patch adds functional checks to prevent writing to the $MFT file via direct file writes or memory-mapped writes in the NTFS driver. This modifies reachable core logic for the NTFS filesystem and should be fuzzed to ensure the checks correctly prevent unauthorized access without causing regressions.",
  "WorthFuzzing": true
}