powerpc/irq: Fix missing r2 clobber in PCREL inline assembly (CVE-2026-93259) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-93259

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

Answer in brief

CVE-2026-93259 records a Unknown severity vulnerability in powerpc/irq: Fix missing r2 clobber in PCREL inline assembly. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 24, 2026Updated Sep 24, 2026Source checked Sep 25, 2026First seen by HOL Sep 25, 2026Material review Sep 24, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=7e3a68be42e10f5fa5890e97afc0afd992355bc3 <dcc442a49c0f540193910dacdca7506bcadc7ec5 \|\| >=7e3a68be42e10f5fa5890e97afc0afd992355bc3 <602ee44415f3eaa7893f7fc488c7c1d4a0bdbd7a \|\| >=7e3a68be42e10f5fa5890e97afc0afd992355bc3 <90d953002cf0b233dd053a0e7cb67ab79cebd0e3 \|\| >=7e3a68be42e10f5fa5890e97afc0afd992355bc3 <7b0093b638c8f2b94b0778a69fd1ccad54299b29 \|\| >=7e3a68be42e10f5fa5890e97afc0afd992355bc3 <00be69070d91d2be978e752bb117a0a4db0e1281	dcc442a49c0f540193910dacdca7506bcadc7ec5, 602ee44415f3eaa7893f7fc488c7c1d4a0bdbd7a, 90d953002cf0b233dd053a0e7cb67ab79cebd0e3, 7b0093b638c8f2b94b0778a69fd1ccad54299b29, 00be69070d91d2be978e752bb117a0a4db0e1281
Linux/Linuxgeneric	6.4	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to dcc442a49c0f540193910dacdca7506bcadc7ec5 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 24, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 24, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 25, 2026

Sources and claim methodology

Upstream source description

In 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

Quoted source text, attributed separately from HOL analysis.