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CVE-2024-50102

Nov. 12, 2024, 3:08 p.m.

CVSS Score

5.5 / 10

Products Impacted

Vendor Product Versions
linux
  • linux_kernel
  • *, 6.12

Description

In the Linux kernel, the following vulnerability has been resolved: x86: fix user address masking non-canonical speculation issue It turns out that AMD has a "Meltdown Lite(tm)" issue with non-canonical accesses in kernel space. And so using just the high bit to decide whether an access is in user space or kernel space ends up with the good old "leak speculative data" if you have the right gadget using the result: CVE-2020-12965 “Transient Execution of Non-Canonical Accesses“ Now, the kernel surrounds the access with a STAC/CLAC pair, and those instructions end up serializing execution on older Zen architectures, which closes the speculation window. But that was true only up until Zen 5, which renames the AC bit [1]. That improves performance of STAC/CLAC a lot, but also means that the speculation window is now open. Note that this affects not just the new address masking, but also the regular valid_user_address() check used by access_ok(), and the asm version of the sign bit check in the get_user() helpers. It does not affect put_user() or clear_user() variants, since there's no speculative result to be used in a gadget for those operations.

Weaknesses

CWE-203
Observable Discrepancy

The product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor, which exposes security-relevant information about the state of the product, such as whether a particular operation was successful or not.

CWE ID: 203

Date

Published: Nov. 5, 2024, 6:15 p.m.

Last Modified: Nov. 12, 2024, 3:08 p.m.

Status : Analyzed

CVE has been recently published to the CVE List and has been received by the NVD.

More info

Source

416baaa9-dc9f-4396-8d5f-8c081fb06d67

CPEs

Type Vendor Product Version Update Edition Language Software Edition Target Software Target Hardware Other Information
o linux linux_kernel / / / / / / / /
o linux linux_kernel 6.12 rc1 / / / / / /
o linux linux_kernel 6.12 rc2 / / / / / /
o linux linux_kernel 6.12 rc3 / / / / / /
o linux linux_kernel 6.12 rc4 / / / / / /

CVSS Data

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

LOW

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

NONE

Availability Impact

NONE

Base Score
5.5
Exploitability Score
1.8
Impact Score
3.6
Base Severity
MEDIUM
CVSS Vector String

The CVSS vector string provides an in-depth view of the vulnerability metrics.

View Vector String

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

References

https://git.kernel.org/ 416baaa9-dc9f-4396-8d5f-8c081fb06d67

https://git.kernel.org/ 416baaa9-dc9f-4396-8d5f-8c081fb06d67