Linux Kernel kernel crypto subsystem Out-Of-Bounds Write Rated 7.1 CVSS

Status: UPDATED  |  Advisory ID: CVE-2026-31698

Key Details

Affected Products, Subsystems & Sectors

What to Know

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

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

When retrieving the PDH cert, don't attempt to copy the blobs 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 ffff8885c4ab8aa0 by task syz.0.186/21033

CPU: 51 UID: 0 PID: 21033 Comm: syz.0.186 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 34.84.12-0 11/17/2025

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_pdh_export+0x3d3/0x7c0 ../drivers/crypto/ccp/sev-dev.c:2347

sev_ioctl+0x2a2/0x490 ../drivers/crypto/ccp/sev-dev.c:2568

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. (NVD)

What to Do

Monitor Linux's and Siemens's web pages for any future patch releases.

References