CVE-2026-31590

Summary

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

KVM: SEV: Drop WARN on large size for KVM_MEMORY_ENCRYPT_REG_REGION

Drop the WARN in sev_pin_memory() on npages overflowing an int, as the WARN is comically trivially to trigger from userspace, e.g. by doing:

struct kvm_enc_region range = { .addr = 0, .size = -1ul, };

__vm_ioctl(vm, KVM_MEMORY_ENCRYPT_REG_REGION, &range);

Note, the checks in sev_mem_enc_register_region() that presumably exist to verify the incoming address+size are completely worthless, as both "addr" and "size" are u64s and SEV is 64-bit only, i.e. they can't be greater than ULONG_MAX. That wart will be cleaned up in the near future.

if (range->addr > ULONG_MAX || range->size > ULONG_MAX)
	return -EINVAL;

Opportunistically add a comment to explain why the code calculates the number of pages the "hard" way, e.g. instead of just shifting @ulen.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/6a8e3c82122737529b25ef2a048fbcc569d8c055
• https://git.kernel.org/stable/c/a703933bcfa5cc76ca10e2048464600e74136099
• https://git.kernel.org/stable/c/abcd43ff579abd0a654bb4636086e78819dd5f4c
• https://git.kernel.org/stable/c/b670833749ffd8681361db2bb047c6f2e3075f3a
• https://git.kernel.org/stable/c/ab423e5892826202a660b5ac85d1125b0e8301a5
• https://git.kernel.org/stable/c/28cc13ca20431b127d42d84ba10898d03e2c8267
• https://git.kernel.org/stable/c/c29ff288a2d97a6f4640a498a367cf0eb91312eb
• https://git.kernel.org/stable/c/1cba4dcd795daf6d257122779fb6a349edf03914
• https://git.kernel.org/stable/c/8acffeef5ef720c35e513e322ab08e32683f32f2

• ←Previous
• Next→