CVE-2026-74671

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

ima: fix out-of-bounds read in xattr_verify()

The digest-length check in xattr_verify() mixes int and size_t:

if (xattr_len - sizeof(xattr_value->type) - hash_start >=

iint->ima_hash->length)

sizeof() yields size_t, so the usual arithmetic conversions promote

the whole left-hand side to unsigned 64-bit before the subtraction

runs. For a truncated xattr this underflows instead of going negative:

a 1-byte IMA_XATTR_DIGEST_NG xattr (xattr_len == 1, hash_start == 1)

turns "1 - 1 - 1" into SIZE_MAX, which is trivially >= ima_hash->length.

The check then passes and the following memcmp() reads

iint->ima_hash->length bytes starting past the end of the buffer

vfs_getxattr_alloc() allocated for it.

Nothing upstream clamps xattr_len back into a safe range first:

ima_get_hash_algo() only special-cases xattr_len < 2 to pick a default

algorithm, and evm_verifyxattr() returns INTEGRITY_UNKNOWN rather than

failing when no HMAC key is loaded, so a truncated security.ima value

reaches the length check as-is.

Rewrite the comparison so every operand stays a signed int and no

implicit conversion to size_t can occur.