In the Linux kernel, the following vulnerability has been resolved:
ext4: fix BUG_ON() when directory entry has invalid rec_len
The rec_len field in the directory entry has to be a multiple of 4. A corrupted filesystem image can be used to hit a BUG() in ext4_rec_len_to_disk(), called from make_indexed_dir().
------------[ cut here ]------------ kernel BUG at fs/ext4/ext4.h:2413! ... RIP: 0010:make_indexed_dir+0x53f/0x5f0 ... Call Trace: <TASK> ? add_dirent_to_buf+0x1b2/0x200 ext4_add_entry+0x36e/0x480 ext4_add_nondir+0x2b/0xc0 ext4_create+0x163/0x200 path_openat+0x635/0xe90 do_filp_open+0xb4/0x160 ? __create_object.isra.0+0x1de/0x3b0 ? _raw_spin_unlock+0x12/0x30 do_sys_openat2+0x91/0x150 __x64_sys_open+0x6c/0xa0 do_syscall_64+0x3c/0x80 entry_SYSCALL_64_after_hwframe+0x46/0xb0
The fix simply adds a call to ext4_check_dir_entry() to validate the directory entry, returning -EFSCORRUPTED if the entry is invalid.
| Software | From | Fixed in |
|---|---|---|
| linux / linux_kernel | - | 5.4.224 |
| linux / linux_kernel | 5.5 | 5.10.154 |
| linux / linux_kernel | 5.11 | 5.15.78 |
| linux / linux_kernel | 5.16 | 6.0.8 |
| linux / linux_kernel | 6.1-rc1 | 6.1-rc1.x |
| linux / linux_kernel | 6.1-rc2 | 6.1-rc2.x |
| linux / linux_kernel | 6.1-rc3 | 6.1-rc3.x |