CVE-2024-44942

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

f2fs: fix to do sanity check on F2FSINLINEDATA 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:f2fswriteinlinedata+0x781/0x790 fs/f2fs/inline.c:258 Call Trace: f2fswritesingledatapage+0xb65/0x1d60 fs/f2fs/data.c:2834 f2fswritecachepages fs/f2fs/data.c:3133 [inline] _f2fswritedatapages fs/f2fs/data.c:3288 [inline] f2fswritedatapages+0x1efe/0x3a90 fs/f2fs/data.c:3315 dowritepages+0x35b/0x870 mm/page-writeback.c:2612 _writebacksingleinode+0x165/0x10b0 fs/fs-writeback.c:1650 writebacksbinodes+0x905/0x1260 fs/fs-writeback.c:1941 wbwriteback+0x457/0xce0 fs/fs-writeback.c:2117 wbdowriteback fs/fs-writeback.c:2264 [inline] wbworkfn+0x410/0x1090 fs/fs-writeback.c:2304 processonework kernel/workqueue.c:3254 [inline] processscheduledworks+0xa12/0x17c0 kernel/workqueue.c:3335 workerthread+0x86d/0xd70 kernel/workqueue.c:3416 kthread+0x2f2/0x390 kernel/kthread.c:388 retfromfork+0x4d/0x80 arch/x86/kernel/process.c:147 retfromforkasm+0x1a/0x30 arch/x86/entry/entry64.S:244

The root cause is: inlinedata 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 f2fsbug_on() during dirty page writeback.

Let's add sanity check on F2FSINLINEDATA flag in inode during GC, so that, it can forbid migrating inline_data inode's data block for fixing.