CVE-2025-37929: arm64: errata: Add missing sentinels to Spectre-BHB MIDR arrays
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 spectrebhbloopaffected() 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 ismidrinrangelist() will walk off the end when it doesn't find a match. With UBSAN enabled, this leads to a crash during boot when ismidrinrangelist() is inlined (which was more common prior to c8c2647e69be ("arm64: Make midrinrangelist() an exported function")):
| Internal error: aarch64 BRK: 00000000f2000001 [#1] PREEMPT SMP | pstate: 804000c5 (Nzcv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--) | pc : spectrebhbloopaffected+0x28/0x30 | lr : isspectrebhbaffected+0x170/0x190 | [...] | Call trace: | spectrebhbloopaffected+0x28/0x30 | updatecpucapabilities+0xc0/0x184 | initcpufeatures+0x188/0x1a4 | cpuinfostorebootcpu+0x4c/0x60 | smppreparebootcpu+0x38/0x54 | startkernel+0x8c/0x478 | primaryswitched+0xc8/0xd4 | Code: 6b09011f 54000061 52801080 d65f03c0 (d4200020) | ---[ end trace 0000000000000000 ]--- | Kernel panic - not syncing: aarch64 BRK: Fatal exception
Add the missing sentinel entries.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
debian/linuxto a version that resolves this vulnerability.Fixed in 6.1.176-1Fixed in 6.1.190-1Fixed in 6.12.107-1Fixed in 6.12.115-2Fixed in 7.2.12-1Fixed in 7.2.15-1 - Compensating control
Add the missing sentinel entries to the Spectre-BHB MIDR arrays used by the arm64 workaround, so is_midr_in_range_list() does not walk past the end of the arrays when no CPU match is found.
Event History
Frequently Asked Questions
What is the severity of CVE-2025-37929?
CVE-2025-37929 has been classified with a moderate severity rating as it involves a workaround for Spectre-BHB in the Linux kernel.
How do I fix CVE-2025-37929?
To fix CVE-2025-37929, ensure that your Linux kernel is updated to the latest stable version that includes the patch for this vulnerability.
What systems are affected by CVE-2025-37929?
CVE-2025-37929 affects the Linux kernel across various versions where the Spectre-BHB mitigation has not been properly applied.
What is the nature of the vulnerability in CVE-2025-37929?
The vulnerability in CVE-2025-37929 relates to missing sentinels in the Spectre-BHB MIDR arrays for certain ARM processors.
Is there a public exploit available for CVE-2025-37929?
As of now, there are no publicly known exploits specifically targeting CVE-2025-37929.