CVE-2026-31699

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

crypto: ccp: Don't attempt to copy CSR to userspace if PSP command failed

When retrieving the PEK CSR, don't attempt to copy the blob to userspace

if the firmware command failed. If the failure was due to an invalid

length, i.e. the userspace buffer+length was too small, copying the number

of bytes _firmware_ requires will overflow the kernel-allocated buffer and

leak data to userspace.

BUG: KASAN: slab-out-of-bounds in instrument_copy_to_user ../include/linux/instrumented.h:129 [inline]

BUG: KASAN: slab-out-of-bounds in _inline_copy_to_user ../include/linux/uaccess.h:205 [inline]

BUG: KASAN: slab-out-of-bounds in _copy_to_user+0x66/0xa0 ../lib/usercopy.c:26

Read of size 2084 at addr ffff898144612e20 by task syz.9.219/21405

CPU: 14 UID: 0 PID: 21405 Comm: syz.9.219 Tainted: G U O 7.0.0-smp-DEV #28 PREEMPTLAZY

Tainted: [U]=USER, [O]=OOT_MODULE

Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 12.62.0-0 11/19/2025

Call Trace:

<TASK>

dump_stack_lvl+0xc5/0x110 ../lib/dump_stack.c:120

print_address_description ../mm/kasan/report.c:378 [inline]

print_report+0xbc/0x260 ../mm/kasan/report.c:482

kasan_report+0xa2/0xe0 ../mm/kasan/report.c:595

check_region_inline ../mm/kasan/generic.c:-1 [inline]

kasan_check_range+0x264/0x2c0 ../mm/kasan/generic.c:200

instrument_copy_to_user ../include/linux/instrumented.h:129 [inline]

_inline_copy_to_user ../include/linux/uaccess.h:205 [inline]

_copy_to_user+0x66/0xa0 ../lib/usercopy.c:26

copy_to_user ../include/linux/uaccess.h:236 [inline]

sev_ioctl_do_pek_csr+0x31f/0x590 ../drivers/crypto/ccp/sev-dev.c:1872

sev_ioctl+0x3a4/0x490 ../drivers/crypto/ccp/sev-dev.c:2562

vfs_ioctl ../fs/ioctl.c:51 [inline]

__do_sys_ioctl ../fs/ioctl.c:597 [inline]

__se_sys_ioctl+0x11d/0x1b0 ../fs/ioctl.c:583

do_syscall_x64 ../arch/x86/entry/syscall_64.c:63 [inline]

do_syscall_64+0xe0/0x800 ../arch/x86/entry/syscall_64.c:94

entry_SYSCALL_64_after_hwframe+0x76/0x7e

</TASK>

WARN if the driver says the command succeeded, but the firmware error code

says otherwise, as __sev_do_cmd_locked() is expected to return -EIO on any

firwmware error.