CVE-2025-37929: debian linux Null Dereference — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: arm64: errata: Add missing sentinels to Spectre-BHB MIDR arrays Commit a5951389e58d ("arm64: errata: Add newer ARM cores to the spectre_bhb_loop_affected() lists") added some additional CPUs to the Spectre-BHB workaround, including some new arrays for designs that require new 'k' values for the workaround to be effective. Unfortunately, the new arrays omitted the sentinel entry and so is_midr_in_range_list() will walk off the end when it doesn't find a match. With UBSAN enabled, this leads to a crash during boot when is_midr_in_range_list() is inlined (which was more common prior to c8c2647e69be ("arm64: Make _midr_in_range_list() an exported function")): | Internal error: aarch64 BRK: 00000000f2000001 [#1] PREEMPT SMP | pstate: 804000c5 (Nzcv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--) | pc : spectre_bhb_loop_affected+0x28/0x30 | lr : is_spectre_bhb_affected+0x170/0x190 | [...] | Call trace: | spectre_bhb_loop_affected+0x28/0x30 | update_cpu_capabilities+0xc0/0x184 | init_cpu_features+0x188/0x1a4 | cpuinfo_store_boot_cpu+0x4c/0x60 | smp_prepare_boot_cpu+0x38/0x54 | start_kernel+0x8c/0x478 | __primary_switched+0xc8/0xd4 | Code: 6b09011f 54000061 52801080 d65f03c0 (d4200020) | ---[ end trace 0000000000000000 ]--- | Kernel panic - not syncing: aarch64 BRK: Fatal exception Add the missing sentinel entries.

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CVSS v3.1 Score

5.5

MEDIUM

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

Weakness Type (CWE)

CWE-476 CWE-476

Affected Products

Vendor	Product	Versions
linux	linux_kernel	6.1.135 — 6.1.138
linux	linux_kernel	6.6.88 — 6.6.90
linux	linux_kernel	6.12.24 — 6.12.28
linux	linux_kernel	6.13.12 — 6.14
linux	linux_kernel	6.14.3 — 6.14.6
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
debian	debian_linux	All

References

Advisories & Patches

https://git.kernel.org/stable/c/090c8714efe1c3c470301cc2f794c1ee2a57746c https://git.kernel.org/stable/c/333579202f09e260e8116321df4c55f80a19b160 https://git.kernel.org/stable/c/3821cae9bd5a99a42d3d0be1b58e41f072cd4c4c https://git.kernel.org/stable/c/446289b8b36b2ee98dabf6388acbddcc33ed41be https://git.kernel.org/stable/c/6266b3509b2c6ebf2f9daf2239ff8eb60c5f5bd3 https://git.kernel.org/stable/c/e68da90ac00d8b681561aeb8f5d6c47af3a04861 https://git.kernel.org/stable/c/fee4d171451c1ad9e8aaf65fc0ab7d143a33bd72

Other References

https://lists.debian.org/debian-lts-announce/2025/08/msg00010.html

Frequently Asked Questions

What is CVE-2025-37929? +

In the Linux kernel, the following vulnerability has been resolved: arm64: errata: Add missing sentinels to Spectre-BHB MIDR arrays Commit a5951389e58d ("arm64: errata: Add newer ARM cores to the spectre_bhb_loop_affected() lists") added some additional CPUs to the Spectre-BHB workaround, including some new arrays for designs that require new 'k' values for the workaround to be effective. Unfortunately, the new arrays omitted the sentinel entry and so is_midr_in_range_list() will walk off the end when it doesn't find a match. With UBSAN enabled, this leads to a crash during boot when is_midr_in_range_list() is inlined (which was more common prior to c8c2647e69be ("arm64: Make _midr_in_range_list() an exported function")): | Internal error: aarch64 BRK: 00000000f2000001 [#1] PREEMPT SMP | pstate: 804000c5 (Nzcv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--) | pc : spectre_bhb_loop_affected+0x28/0x30 | lr : is_spectre_bhb_affected+0x170/0x190 | [...] | Call trace: | spectre_bhb_loop_affected+0x28/0x30 | update_cpu_capabilities+0xc0/0x184 | init_cpu_features+0x188/0x1a4 | cpuinfo_store_boot_cpu+0x4c/0x60 | smp_prepare_boot_cpu+0x38/0x54 | start_kernel+0x8c/0x478 | __primary_switched+0xc8/0xd4 | Code: 6b09011f 54000061 52801080 d65f03c0 (d4200020) | ---[ end trace 0000000000000000 ]--- | Kernel panic - not syncing: aarch64 BRK: Fatal exception Add the missing sentinel entries. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-37929? +

CVE-2025-37929 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-37929? +

CVE-2025-37929 affects products from debian, linux, specifically: debian_linux, linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-37929? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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