GHSA-8H7F-5WC3-64CF
Vulnerability from github – Published: 2026-09-24 18:31 – Updated: 2026-09-24 18:31In 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.
{
"affected": [],
"aliases": [
"CVE-2026-93259"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-24T16:17:22Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\npowerpc/irq: Fix missing r2 clobber in PCREL inline assembly\n\nIn CONFIG_PPC_KERNEL_PCREL mode, r2 is no longer reserved for the TOC\npointer and is available as a caller-saved register [0].\n\nBoth call_do_irq() and call_do_softirq() use inline assembly to call\nfunctions with stack switching, but fail to list r2 in their clobber\nlists. This causes the compiler to assume r2 is preserved across these\ncalls, leading to register corruption when the called functions\n(__do_irq and __do_softirq) clobber r2.\n\nAs a result of this kernel crash during interrupt handling is seen and\nthe kernel fails to boot:\n\nBUG: Unable to handle kernel data access on write at 0xc000000404697638\nFaulting instruction address: 0xc0000000000181ec\nOops: Kernel access of bad area, sig: 11 [#1]\nNIP [c0000000000181ec] __do_IRQ+0x6c/0xc0\n\nWith older GCC, the compiler would conservatively allocate\ncallee-saved registers (like r31) for values spanning function calls,\naccidentally avoiding the bug:\n\n\u003c__do_IRQ\u003e:\n00 00 00 60 \tnop\na6 02 08 7c \tmflr r0\nf8 ff e1 fb \tstd r31,-8(r1)\nf0 ff c1 fb \tstd r30,-16(r1)\n2d 03 10 06 \tpla r31,53297316\n\n...\n\n3d e8 ff 4b \tbl c0000000000165ac \u003c__do_irq\u003e\n00 00 21 e8 \tld r1,0(r1)\n28 00 4d e9 \tld r10,40(r13)\n40 00 21 38 \taddi r1,r1,64\n2a f9 aa 7f \tstdx r29,r10,r31\n\nWith newer GCC 14, the compiler uses r2 for such values, exposing the\nmissing clobber specification:\n\n\u003c__do_IRQ\u003e:\n00 00 00 60 nop\na6 02 08 7c mflr r0\nf0 ff c1 fb std r30,-16(r1)\nf8 ff e1 fb std r31,-8(r1)\n29 02 10 06 pla r2,36252592 # c0000000022aadc0 \u003c__irq_regs\u003e\n\n...\n\n85 dc ff 4b \tbl c000000000015ee0 \u003c__do_irq\u003e\n00 00 21 e8 \tld r1,0(r1)\n28 00 2d e9 \tld r9,40(r13)\n30 00 21 38 \taddi r1,r1,48\n2a 11 c9 7f \tstdx r30,r9,r2\n\nFix this by adding r2 to the clobber list for both call_do_irq() and\ncall_do_softirq() when CONFIG_PPC_KERNEL_PCREL is enabled.\n\n[0]: https://www.mail-archive.com/gcc-patches@gcc.gnu.org/msg313226.html",
"id": "GHSA-8h7f-5wc3-64cf",
"modified": "2026-09-24T18:31:24Z",
"published": "2026-09-24T18:31:24Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-93259"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/00be69070d91d2be978e752bb117a0a4db0e1281"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/602ee44415f3eaa7893f7fc488c7c1d4a0bdbd7a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7b0093b638c8f2b94b0778a69fd1ccad54299b29"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/90d953002cf0b233dd053a0e7cb67ab79cebd0e3"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/dcc442a49c0f540193910dacdca7506bcadc7ec5"
}
],
"schema_version": "1.4.0",
"severity": []
}
Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline
Sightings and recorded dates, grouped by day · UTC
How durations are calculated
Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.
Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.
Loading timeline…
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.