powerpc/irq: Fix missing r2 clobber in PCREL inline assembly

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-93259
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-24 16:17:22 UTC
Updated2026-09-24 16:17:22 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: powerpc/irq: Fix missing r2 clobber in PCREL inline assembly In CONFIG_PPC_KERNEL_PCREL mode, r2 is no longer reserved for the TOC pointer and is available as a caller-saved register [0]. Both call_do_irq() and call_do_softirq() use inline assembly to call functions with stack switching, but fail to list r2 in their clobber lists. This causes the compiler to assume r2 is preserved across these calls, leading to register corruption when the called functions (__do_irq and __do_softirq) clobber r2. As a result of this kernel crash during interrupt handling is seen and the kernel fails to boot: BUG: Unable to handle kernel data access on write at 0xc000000404697638 Faulting instruction address: 0xc0000000000181ec Oops: Kernel access of bad area, sig: 11 [#1] NIP [c0000000000181ec] __do_IRQ+0x6c/0xc0 With older GCC, the compiler would conservatively allocate callee-saved registers (like r31) for values spanning function calls, accidentally avoiding the bug: <__do_IRQ>: 00 00 00 60 nop a6 02 08 7c mflr r0 f8 ff e1 fb std r31,-8(r1) f0 ff c1 fb std r30,-16(r1) 2d 03 10 06 pla r31,53297316 ... 3d e8 ff 4b bl c0000000000165ac <__do_irq> 00 00 21 e8 ld r1,0(r1) 28 00 4d e9 ld r10,40(r13) 40 00 21 38 addi r1,r1,64 2a f9 aa 7f stdx r29,r10,r31 With newer GCC 14, the compiler uses r2 for such values, exposing the missing clobber specification: <__do_IRQ>: 00 00 00 60 nop a6 02 08 7c mflr r0 f0 ff c1 fb std r30,-16(r1) f8 ff e1 fb std r31,-8(r1) 29 02 10 06 pla r2,36252592 # c0000000022aadc0 <__irq_regs> ... 85 dc ff 4b bl c000000000015ee0 <__do_irq> 00 00 21 e8 ld r1,0(r1) 28 00 2d e9 ld r9,40(r13) 30 00 21 38 addi r1,r1,48 2a 11 c9 7f stdx r30,r9,r2 Fix this by adding r2 to the clobber list for both call_do_irq() and call_do_softirq() when CONFIG_PPC_KERNEL_PCREL is enabled. [0]: https://www.mail-archive.com/[email protected]/msg313226.html

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 7e3a68be42e10f5fa5890e97afc0afd992355bc3 dcc442a49c0f540193910dacdca7506bcadc7ec5 git Not specified
CNA Linux Linux affected 7e3a68be42e10f5fa5890e97afc0afd992355bc3 602ee44415f3eaa7893f7fc488c7c1d4a0bdbd7a git Not specified
CNA Linux Linux affected 7e3a68be42e10f5fa5890e97afc0afd992355bc3 90d953002cf0b233dd053a0e7cb67ab79cebd0e3 git Not specified
CNA Linux Linux affected 7e3a68be42e10f5fa5890e97afc0afd992355bc3 7b0093b638c8f2b94b0778a69fd1ccad54299b29 git Not specified
CNA Linux Linux affected 7e3a68be42e10f5fa5890e97afc0afd992355bc3 00be69070d91d2be978e752bb117a0a4db0e1281 git Not specified
CNA Linux Linux affected 6.4 Not specified
CNA Linux Linux unaffected 6.4 semver Not specified
CNA Linux Linux unaffected 6.6.157 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.110 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.52 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.6 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/dcc442a49c0f540193910dacdca7506bcadc7ec5 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/7b0093b638c8f2b94b0778a69fd1ccad54299b29 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/00be69070d91d2be978e752bb117a0a4db0e1281 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/90d953002cf0b233dd053a0e7cb67ab79cebd0e3 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/602ee44415f3eaa7893f7fc488c7c1d4a0bdbd7a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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