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:

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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.