From: Chao Yu chao@kernel.org
[ Upstream commit 12662d19467b391b5b509ac5e9ab4f583c6dde16 ]
As Wenqing reported in bugzilla:
https://bugzilla.kernel.org/show_bug.cgi?id=215765
It will cause a kernel panic with steps: - mkdir mnt - mount tmp40.img mnt - ls mnt
folio_mark_dirty+0x33/0x50 f2fs_add_regular_entry+0x541/0xad0 [f2fs] f2fs_add_dentry+0x6c/0xb0 [f2fs] f2fs_do_add_link+0x182/0x230 [f2fs] __recover_dot_dentries+0x2d6/0x470 [f2fs] f2fs_lookup+0x5af/0x6a0 [f2fs] __lookup_slow+0xac/0x200 lookup_slow+0x45/0x70 walk_component+0x16c/0x250 path_lookupat+0x8b/0x1f0 filename_lookup+0xef/0x250 user_path_at_empty+0x46/0x70 vfs_statx+0x98/0x190 __do_sys_newlstat+0x41/0x90 __x64_sys_newlstat+0x1a/0x30 do_syscall_64+0x37/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xae
The root cause is for special file: e.g. character, block, fifo or socket file, f2fs doesn't assign address space operations pointer array for mapping->a_ops field, so, in a fuzzed image, if inline_dots flag was tagged in special file, during lookup(), when f2fs runs into __recover_dot_dentries(), it will cause NULL pointer access once f2fs_add_regular_entry() calls a_ops->set_dirty_page().
Fixes: 510022a85839 ("f2fs: add F2FS_INLINE_DOTS to recover missing dot dentries") Reported-by: Wenqing Liu wenqingliu0120@gmail.com Signed-off-by: Chao Yu chao.yu@oppo.com Signed-off-by: Jaegeuk Kim jaegeuk@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/f2fs/namei.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c index 5f213f05556d..53273aec2627 100644 --- a/fs/f2fs/namei.c +++ b/fs/f2fs/namei.c @@ -460,6 +460,13 @@ static int __recover_dot_dentries(struct inode *dir, nid_t pino) return 0; }
+ if (!S_ISDIR(dir->i_mode)) { + f2fs_err(sbi, "inconsistent inode status, skip recovering inline_dots inode (ino:%lu, i_mode:%u, pino:%u)", + dir->i_ino, dir->i_mode, pino); + set_sbi_flag(sbi, SBI_NEED_FSCK); + return -ENOTDIR; + } + err = f2fs_dquot_initialize(dir); if (err) return err;