CVE-2022-49428

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

f2fs: fix to do sanity check on inline_dots inode

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 doesnt 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().

Affected Software 

References  

• https://git.kernel.org/stable/c/12662d19467b391b5b509ac5e9ab4f583c6dde16
• https://git.kernel.org/stable/c/250e5a6be52a6b9d82fe91976c83cc158868b4e9
• https://git.kernel.org/stable/c/2f46160d0a19b13bfe96c0dd50eed5c5d253ab7a
• https://git.kernel.org/stable/c/34f48ce5d5936eea33e3b6415403e57eb84aff97