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CVE-2024-50182

Nov. 29, 2024, 8:38 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: secretmem: disable memfd_secret() if arch cannot set direct map Return -ENOSYS from memfd_secret() syscall if !can_set_direct_map(). This is the case for example on some arm64 configurations, where marking 4k PTEs in the direct map not present can only be done if the direct map is set up at 4k granularity in the first place (as ARM's break-before-make semantics do not easily allow breaking apart large/gigantic pages). More precisely, on arm64 systems with !can_set_direct_map(), set_direct_map_invalid_noflush() is a no-op, however it returns success (0) instead of an error. This means that memfd_secret will seemingly "work" (e.g. syscall succeeds, you can mmap the fd and fault in pages), but it does not actually achieve its goal of removing its memory from the direct map. Note that with this patch, memfd_secret() will start erroring on systems where can_set_direct_map() returns false (arm64 with CONFIG_RODATA_FULL_DEFAULT_ENABLED=n, CONFIG_DEBUG_PAGEALLOC=n and CONFIG_KFENCE=n), but that still seems better than the current silent failure. Since CONFIG_RODATA_FULL_DEFAULT_ENABLED defaults to 'y', most arm64 systems actually have a working memfd_secret() and aren't be affected. From going through the iterations of the original memfd_secret patch series, it seems that disabling the syscall in these scenarios was the intended behavior [1] (preferred over having set_direct_map_invalid_noflush return an error as that would result in SIGBUSes at page-fault time), however the check for it got dropped between v16 [2] and v17 [3], when secretmem moved away from CMA allocations. [1]: https://lore.kernel.org/lkml/20201124164930.GK8537@kernel.org/ [2]: https://lore.kernel.org/lkml/20210121122723.3446-11-rppt@kernel.org/#t [3]: https://lore.kernel.org/lkml/20201125092208.12544-10-rppt@kernel.org/

Weaknesses

Date

Published: Nov. 8, 2024, 6:15 a.m.

Last Modified: Nov. 29, 2024, 8:38 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 / / / / / / / /
o linux linux_kernel / / / / / / / /
o linux linux_kernel / / / / / / / /
o linux linux_kernel 6.12 rc1 / / / / / /
o linux linux_kernel 6.12 rc2 / / / / / /

CVSS Data

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

LOW

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

HIGH

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:N/I:N/A:H

References

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

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

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

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

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