CVE-2022-49879 Information

Description

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: ? 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.

Reference

https://git.kernel.org/stable/c/156451a67b93986fb07c274ef6995ff40766c5ad https://git.kernel.org/stable/c/17a0bc9bd697f75cfdf9b378d5eb2d7409c91340 https://git.kernel.org/stable/c/2fa24d0274fbf913b56ee31f15bc01168669d909 https://git.kernel.org/stable/c/999cff2b6ce3b45c08abf793bf55534777421327 https://git.kernel.org/stable/c/ce1ee2c8827fb6493e91acbd50f664cf2a972c3d