powerpc/irq: Fix missing r2 clobber in PCREL inline assembly
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/gcc-patches@gcc.gnu.org/msg313226.html
- Published
- Sep 24, 2026
- Updated
- Sep 24, 2026
- EPSS
- 0.2% · 7th percentile
- CWE
- —
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Report tools
Action score
0
Monitor
Low priority for now.
- CVSS
- 0 / 40 · —
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.2%
Affected systems
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Versions reported by the vendor
Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.
Linux Linux
- 6.4affected
- 7e3a68be42e10f5fa5890e97afc0afd992355bc3 and later · before dcc442a49c0f540193910dacdca7506bcadc7ec5affected · git
- 7e3a68be42e10f5fa5890e97afc0afd992355bc3 and later · before 602ee44415f3eaa7893f7fc488c7c1d4a0bdbd7aaffected · git
- 7e3a68be42e10f5fa5890e97afc0afd992355bc3 and later · before 90d953002cf0b233dd053a0e7cb67ab79cebd0e3affected · git
- 7e3a68be42e10f5fa5890e97afc0afd992355bc3 and later · before 7b0093b638c8f2b94b0778a69fd1ccad54299b29affected · git
- 7e3a68be42e10f5fa5890e97afc0afd992355bc3 and later · before 00be69070d91d2be978e752bb117a0a4db0e1281affected · git
- before 6.4not affected · semver
- 6.6.157 and later · up to and including 6.6.*not affected · semver
- 6.12.110 and later · up to and including 6.12.*not affected · semver
- 6.18.52 and later · up to and including 6.18.*not affected · semver
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:13 | linux | before 6.12.111-1 | 6.12.111-1 |
| Debian:14 | linux | before 7.2.6-1 | 7.2.6-1 |
Same product
linux: all recordsOther highest-scoring records for the same primary product.
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Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Linux Linux | 00be69070d91d2be978e752bb117a0a4db0e1281 | Vendor (CNA) |
| Linux Linux | 602ee44415f3eaa7893f7fc488c7c1d4a0bdbd7a | Vendor (CNA) |
| Linux Linux | 7b0093b638c8f2b94b0778a69fd1ccad54299b29 | Vendor (CNA) |
| Linux Linux | 90d953002cf0b233dd053a0e7cb67ab79cebd0e3 | Vendor (CNA) |
| Linux Linux | dcc442a49c0f540193910dacdca7506bcadc7ec5 | Vendor (CNA) |
| azl3 kernel 6.6.150.1-1 on Azure Linux 3.0 | Release Notes | Microsoft (MSRC) |
| debian:linux | 6.12.111-1 · Debian:13 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
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No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
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No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
No CVSS vector for this record, so attack conditions can't be derived.
Weakness class (CWE)
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Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
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Noroxi analysis
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We use this product, ask for helpChange log
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References
- git.kernel.org/stable/c/00be69070d91d2be978e752bb117a0a4db0e1281
- git.kernel.org/stable/c/602ee44415f3eaa7893f7fc488c7c1d4a0bdbd7a
- git.kernel.org/stable/c/7b0093b638c8f2b94b0778a69fd1ccad54299b29
- git.kernel.org/stable/c/90d953002cf0b233dd053a0e7cb67ab79cebd0e3
- git.kernel.org/stable/c/dcc442a49c0f540193910dacdca7506bcadc7ec5
Vendor advisories and official records. Exploit/PoC links are deliberately left out.