title: erofs: fix inconsistent per-file compression format
description: In the Linux kernel, the following vulnerability has been resolved:
erofs: fix inconsistent per-file compression format
EROFS can select compression algorithms on a per-file basis, and each
per-file compression algorithm needs to be marked in the on-disk
superblock for initialization.
However, syzkaller can generate inconsistent crafted images that use
an unsupported algorithmtype for specific inodes, e.g. use MicroLZMA
algorithmtype even it's not set in `sbi->available_compr_algs`.  This
can lead to an unexpected "BUG: kernel NULL pointer dereference" if
the corresponding decompressor isn't built-in.
Fix this by checking against `sbi->available_compr_algs` for each
m_algorithmformat request.  Incorrect !erofs_sb_has_compr_cfgs preset
bitmap is now fixed together since it was harmless previously.
affected:
{
product: Linux
vendor: Linux
defaultStatus: unaffected
repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
versions:
version: 8f89926290c4, lessThan: 47467e04816c, status: affected, versionType: git
version: 8f89926290c4, lessThan: 823ba1d21060, status: affected, versionType: git
version: 8f89926290c4, lessThan: eed24b816e50, status: affected, versionType: git
version: 8f89926290c4, lessThan: 118a8cf504d7, status: affected, versionType: git
}
{
product: Linux
vendor: Linux
defaultStatus: affected
repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
versions:
version: 5.16, status: affected
version: 0, lessThan: 5.16, status: unaffected, versionType: custom
version: 6.1.80, lessThanOrEqual: 6.1.*, status: unaffected, versionType: custom
version: 6.6.14, lessThanOrEqual: 6.6.*, status: unaffected, versionType: custom
version: 6.7.2, lessThanOrEqual: 6.7.*, status: unaffected, versionType: custom
version: 6.8, lessThanOrEqual: *, status: unaffected, versionType: original_commit_for_fix
}
