From: Chao Yu chao@kernel.org

[ Upstream commit fc01008c92f40015aeeced94750855a7111b6929 ]

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.

Reported-by: syzbot+848062ba19c8782ca5c8@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-f2fs-devel/000000000000d103ce06174d7ec3@google... Signed-off-by: Chao Yu chao@kernel.org Signed-off-by: Jaegeuk Kim jaegeuk@kernel.org [kovalev: Replaced f2fs_err_ratelimited() with printk_ratelimited() to use a supported function] Signed-off-by: Vasiliy Kovalev kovalev@altlinux.org --- Backport to fix CVE-2024-44942 Link: https://www.cve.org/CVERecord/?id=CVE-2024-44942 --- fs/f2fs/gc.c | 11 +++++++++++ 1 file changed, 11 insertions(+)

diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c index 19d781a3d305a6..64ff51c2f3d642 100644 --- a/fs/f2fs/gc.c +++ b/fs/f2fs/gc.c @@ -1457,6 +1457,17 @@ static int gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum, continue; }

+ if (f2fs_has_inline_data(inode)) { + iput(inode); + set_sbi_flag(sbi, SBI_NEED_FSCK); + printk_ratelimited("%sF2FS-fs (%s): " + "inode %lx has both inline_data flag and " + "data block, nid=%u, ofs_in_node=%u", + KERN_INFO, sbi->sb->s_id, + inode->i_ino, dni.nid, ofs_in_node); + continue; + } + if (!down_write_trylock( &F2FS_I(inode)->i_gc_rwsem[WRITE])) { iput(inode);