CVE-2024-44942

In the Linux kernel, the following vulnerability has been resolved:

f2fs: fix to do sanity check on F2FS_INLINE_DATA flag in inode during GC

syzbot reports a f2fs bug as below:

------------[ cut here ]------------ kernel BUG at fs/f2fs/inline.c:258! CPU: 1 PID: 34 Comm: kworker/u8:2 Not tainted 6.9.0-rc6-syzkaller-00012-g9e4bc4bcae01 #0 RIP: 0010:f2fs_write_inline_data+0x781/0x790 fs/f2fs/inline.c:258 Call Trace: f2fs_write_single_data_page+0xb65/0x1d60 fs/f2fs/data.c:2834 f2fs_write_cache_pages fs/f2fs/data.c:3133 [inline] __f2fs_write_data_pages fs/f2fs/data.c:3288 [inline] f2fs_write_data_pages+0x1efe/0x3a90 fs/f2fs/data.c:3315 do_writepages+0x35b/0x870 mm/page-writeback.c:2612 __writeback_single_inode+0x165/0x10b0 fs/fs-writeback.c:1650 writeback_sb_inodes+0x905/0x1260 fs/fs-writeback.c:1941 wb_writeback+0x457/0xce0 fs/fs-writeback.c:2117 wb_do_writeback fs/fs-writeback.c:2264 [inline] wb_workfn+0x410/0x1090 fs/fs-writeback.c:2304 process_one_work kernel/workqueue.c:3254 [inline] process_scheduled_works+0xa12/0x17c0 kernel/workqueue.c:3335 worker_thread+0x86d/0xd70 kernel/workqueue.c:3416 kthread+0x2f2/0x390 kernel/kthread.c:388 ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

The root cause is: inline_data inode can be fuzzed, so that there may be valid blkaddr in its direct node, once f2fs triggers background GC to migrate the block, it will hit f2fs_bug_on() during dirty page writeback.

Let's add sanity check on F2FS_INLINE_DATA flag in inode during GC, so that, it can forbid migrating inline_data inode's data block for fixing.

This vulnerability is rated as Moderate impact because exploitation requires mounting a crafted file system image, restricting the attack vector to local privileged users or physical media insertion. In Red Hat Enterprise Linux, the F2FS file system is not enabled by default in enterprise kernels, preventing exposure in standard environments. On configurations where F2FS is active, triggering the flaw results in a kernel panic during dirty page writeback, causing a localized denial of service without compromising data confidentiality or integrity.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.