csky: Fix a4/a5 restoration in syscall trace path
Key facts
- Attack vector
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- Privileges required
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- User interaction
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- Attack complexity
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- Impact type
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- Confidentiality · integrity · availability
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- Fix status
- Fixed
No CVSS vector from any source. Fix status from CNA.
Summary
In the Linux kernel, the following vulnerability has been resolved: csky: Fix a4/a5 restoration in syscall trace path The syscall trace path reloads syscall arguments from pt_regs before calling the syscall handler. On C-SKY ABIv2, the 5th and 6th syscall arguments are prepared as stack arguments before invoking syscallid. The current code adjusts sp before loading LSAVE_A4 and LSAVE_A5. Since those offsets are relative to the original pt_regs base, loading them after changing sp fetches the wrong slots. As a result, traced syscalls that use the 5th or 6th argument may receive corrupted arguments. This is visible with mmap2(), which takes six arguments. A small PTRACE_SYSCALL reproducer opens a file and maps one page with: mmap(NULL, 4096, PROT_READ | PROT_EXEC, MAP_PRIVATE, fd, 0) Before the fix, the traced child fails the mmap and exits with 12. After the fix, the mapping succeeds and the child exits with 0. Fix the trace path by loading a4/a5 from pt_regs before changing sp. Tested on: ck860f, linux-4.19.15, C-SKY abiv2
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
- Fix · CNA Linux (Linux) Fixed in 5.5, 5.7
- Fix · CNA Linux (Linux) Fixed in 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110, 6.18.52, 7.2.6, 7.3
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
Not affected: 7 products
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat OpenShift Container Platform 4
- Red Hat OpenShift Container Platform 5
Timeline
- 2026-10-02 Threatist record created from CVE-2026-93167
- 2026-10-03 Alias added: GHSA-fgg4-f5v2-253f
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-10-21 Affected versions changed · Red Hat
- 2026-10-21 CVSS score added · Red Hat
- 2026-11-06 Affected versions changed · Red Hat
References
Other 8
- https://git.kernel.org/stable/c/e9ae8e86eed68bea5d2670eadf61938a43bd2263
- https://git.kernel.org/stable/c/64e3ec7a71d3b715e2567f19f64207f04999bb0c
- https://git.kernel.org/stable/c/863fa63fd1491f201ac819f805a8db98d2a32c3d
- https://git.kernel.org/stable/c/e71a3dc5b8d2ea4d9cfbdb135d6b7777de84212e
- https://git.kernel.org/stable/c/31c81b376e5f058c7f2c94f69719cf7caec2fc3f
- https://git.kernel.org/stable/c/a776afa89424570bfa637ebf812ca281a5732904
- https://git.kernel.org/stable/c/343aa5275484d627c921a42e8e115cae366be5de
- https://git.kernel.org/stable/c/abb81e5ce7d995baa41556b8125fa59e28ba3be8
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Sources
- CVE-2026-93167 · CVE Program
- CVE-2026-93167 · NVD
- FIRST EPSS
- GHSA-fgg4-f5v2-253f · GitHub Advisory Database · CC BY 4.0
- CVE-2026-93167 · Red Hat security data · CC BY 4.0
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