CVE-2026-93167 is a vulnerability in Linux Kernel
Published on September 17, 2026
csky: Fix a4/a5 restoration in syscall trace path
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
Products Associated with CVE-2026-93167
Want to know whenever a new CVE is published for Linux Kernel? stack.watch will email you.
Affected Versions
Linux:- Version e0bbb53843b5fdfe464b099217e3b9d97e8a75d7 and below e9ae8e86eed68bea5d2670eadf61938a43bd2263 is affected.
- Version e0bbb53843b5fdfe464b099217e3b9d97e8a75d7 and below 64e3ec7a71d3b715e2567f19f64207f04999bb0c is affected.
- Version e0bbb53843b5fdfe464b099217e3b9d97e8a75d7 and below 863fa63fd1491f201ac819f805a8db98d2a32c3d is affected.
- Version e0bbb53843b5fdfe464b099217e3b9d97e8a75d7 and below e71a3dc5b8d2ea4d9cfbdb135d6b7777de84212e is affected.
- Version e0bbb53843b5fdfe464b099217e3b9d97e8a75d7 and below 31c81b376e5f058c7f2c94f69719cf7caec2fc3f is affected.
- Version e0bbb53843b5fdfe464b099217e3b9d97e8a75d7 and below a776afa89424570bfa637ebf812ca281a5732904 is affected.
- Version e0bbb53843b5fdfe464b099217e3b9d97e8a75d7 and below 343aa5275484d627c921a42e8e115cae366be5de is affected.
- Version e0bbb53843b5fdfe464b099217e3b9d97e8a75d7 and below abb81e5ce7d995baa41556b8125fa59e28ba3be8 is affected.
- Version 108681048cf728a8570e036c34ebd7daa43133b4 is affected.
- Version 3a5837c692918c229baf63fe7950965d27c48ac2 is affected.
- Version 5.4.47 and below 5.5 is affected.
- Version 5.6.19 and below 5.7 is affected.
- Version 5.7 is affected.
- Before 5.7 is unaffected.
- Version 5.10.270, <= 5.10.* is unaffected.
- Version 5.15.221, <= 5.15.* is unaffected.
- Version 6.1.188, <= 6.1.* is unaffected.
- Version 6.6.157, <= 6.6.* is unaffected.
- Version 6.12.110, <= 6.12.* is unaffected.
- Version 6.18.52, <= 6.18.* is unaffected.
- Version 7.2.6, <= 7.2.* is unaffected.
- Version 7.3-rc1, <= * is unaffected.