{"id":"CVE-2026-93167","summary":"csky: Fix a4/a5 restoration in syscall trace path","details":"In the Linux kernel, the following vulnerability has been resolved:\n\ncsky: Fix a4/a5 restoration in syscall trace path\n\nThe syscall trace path reloads syscall arguments from pt_regs before\ncalling the syscall handler. On C-SKY ABIv2, the 5th and 6th syscall\narguments are prepared as stack arguments before invoking syscallid.\n\nThe current code adjusts sp before loading LSAVE_A4 and LSAVE_A5. Since\nthose offsets are relative to the original pt_regs base, loading them\nafter changing sp fetches the wrong slots. As a result, traced syscalls\nthat use the 5th or 6th argument may receive corrupted arguments.\n\nThis is visible with mmap2(), which takes six arguments. A small\nPTRACE_SYSCALL reproducer opens a file and maps one page with:\n\n  mmap(NULL, 4096, PROT_READ | PROT_EXEC, MAP_PRIVATE, fd, 0)\n\nBefore the fix, the traced child fails the mmap and exits with 12.\nAfter the fix, the mapping succeeds and the child exits with 0.\n\nFix the trace path by loading a4/a5 from pt_regs before changing sp.\n\nTested on: ck860f, linux-4.19.15, C-SKY abiv2","modified":"2026-09-19T03:47:27.086750016Z","published":"2026-09-17T16:11:59.234Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/93xxx/CVE-2026-93167.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/31c81b376e5f058c7f2c94f69719cf7caec2fc3f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/343aa5275484d627c921a42e8e115cae366be5de"},{"type":"WEB","url":"https://git.kernel.org/stable/c/64e3ec7a71d3b715e2567f19f64207f04999bb0c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/863fa63fd1491f201ac819f805a8db98d2a32c3d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a776afa89424570bfa637ebf812ca281a5732904"},{"type":"WEB","url":"https://git.kernel.org/stable/c/abb81e5ce7d995baa41556b8125fa59e28ba3be8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e71a3dc5b8d2ea4d9cfbdb135d6b7777de84212e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e9ae8e86eed68bea5d2670eadf61938a43bd2263"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/93xxx/CVE-2026-93167.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-93167"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"e0bbb53843b5fdfe464b099217e3b9d97e8a75d7"},{"fixed":"e9ae8e86eed68bea5d2670eadf61938a43bd2263"},{"fixed":"64e3ec7a71d3b715e2567f19f64207f04999bb0c"},{"fixed":"863fa63fd1491f201ac819f805a8db98d2a32c3d"},{"fixed":"e71a3dc5b8d2ea4d9cfbdb135d6b7777de84212e"},{"fixed":"31c81b376e5f058c7f2c94f69719cf7caec2fc3f"},{"fixed":"a776afa89424570bfa637ebf812ca281a5732904"},{"fixed":"343aa5275484d627c921a42e8e115cae366be5de"},{"fixed":"abb81e5ce7d995baa41556b8125fa59e28ba3be8"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"0"},{"last_affected":"108681048cf728a8570e036c34ebd7daa43133b4"},{"last_affected":"3a5837c692918c229baf63fe7950965d27c48ac2"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"5.4.47"},{"fixed":"5.5"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"5.6.19"},{"fixed":"5.7"}]}],"versions":["v5.6.18","v5.4.46","v5.4.45","v5.6.17","v5.4.44","v5.6.16","v5.6.15","v5.4.43","v5.6.14","v5.4.42","v5.6.13","v5.4.41","v5.6.12","v5.4.40","v5.6","v5.6.11","v5.4.39","v5.6.10","v5.4.38","v5.6.9","v5.4.37","v5.6.8","v5.4.36","v5.6.7","v5.4.35","v5.6.6","v5.4.34","v5.6.5","v5.4.33","v5.6.4","v5.4.32","v5.6.3","v5.4.31","v5.6.2","v5.4.30","v5.6-rc1","v5.4.29","v5.6.1","v5.4.28","v5.6-rc7","v5.6-rc6","v5.6-rc3","v5.6-rc4","v5.6-rc2","v5.6-rc5","v5.4.27","v5.4.26","v5.4.25","v5.4.24","v5.4.23","v5.4.22","v5.4.21","v5.4.20","v5.4.19","v5.4.18","v5.5","v5.4.17","v5.5-rc5","v5.4.16","v5.5-rc7","v5.5-rc2","v5.5-rc1","v5.4.15","v5.4","v5.4.14","v5.5-rc4","v5.4.13","v5.5-rc3","v5.5-rc6","v5.4.12","v5.4.11","v5.4.10","v5.4.9","v5.4.8","v5.4.7","v5.4.6","v5.4.5","v5.4.4","v5.4.3","v5.4.2","v5.4-rc1","v5.4.1","v5.4-rc6","v5.4-rc3","v5.4-rc4","v5.4-rc8","v5.4-rc7","v5.4-rc5","v5.3","v5.4-rc2","v5.3-rc5","v5.3-rc1","v5.3-rc2","v5.3-rc3","v5.3-rc8","v5.3-rc7","v5.3-rc4","v5.2","v5.3-rc6","v5.2-rc2","v5.2-rc7","v5.2-rc4","v5.2-rc1","v5.2-rc5","v5.2-rc6","v5.2-rc3","v5.1","v5.0-rc8","v5.1-rc7","v5.1-rc1","v5.1-rc6","v5.1-rc5","v5.0","v5.1-rc3","v5.1-rc2","v5.1-rc4","v5.0-rc1","v5.0-rc4","v5.0-rc3","v5.0-rc6","v5.0-rc7","v5.0-rc2","v5.0-rc5","v4.20-rc1","v4.19","v4.20","v4.20-rc7","v4.20-rc5","v4.20-rc6","v4.20-rc4","v4.20-rc2","v4.20-rc3","v4.19-rc2","v4.19-rc8","v4.19-rc4","v4.19-rc1","v4.19-rc7","v4.19-rc6","v4.19-rc5","v4.19-rc3","v4.18","v4.18-rc1","v4.18-rc8","v4.18-rc2","v4.18-rc5","v4.18-rc6","v4.18-rc7","v4.17","v4.18-rc3","v4.18-rc4","v4.17-rc1","v4.17-rc2","v4.17-rc7","v4.17-rc3","v4.17-rc4","v4.16","v4.17-rc6","v4.17-rc5","v4.16-rc7","v4.16-rc4","v4.16-rc1","v4.16-rc2","v4.16-rc5","v4.16-rc3","v4.16-rc6","v4.14","v4.15","v4.15-rc1","v4.15-rc4","v4.15-rc9","v4.15-rc8","v4.15-rc7","v4.15-rc3","v4.15-rc2","v4.15-rc5","v4.15-rc6","v4.14-rc1","v4.14-rc7","v4.14-rc3","v4.13","v4.14-rc8","v4.14-rc4","v4.14-rc6","v4.14-rc2","v4.14-rc5","v4.13-rc2","v4.13-rc1","v4.13-rc3","v4.13-rc7","v4.13-rc4","v4.13-rc5","v4.13-rc6","v4.12-rc1","v4.12","v4.12-rc5","v4.12-rc7","v4.12-rc6","v4.12-rc4","v4.12-rc2","v4.12-rc3","v4.11","v4.11-rc1","v4.11-rc6","v4.11-rc8","v4.11-rc7","v4.11-rc3","v4.11-rc5","v4.11-rc2","v4.11-rc4","v4.10","v4.9","v4.10-rc8","v4.10-rc3","v4.10-rc1","v4.10-rc7","v4.10-rc6","v4.10-rc2","v4.10-rc5","v4.10-rc4","v4.9-rc7","v4.9-rc6","v4.9-rc8","v4.9-rc1","v4.9-rc5","v4.9-rc3","v4.9-rc4","v4.9-rc2","v4.8","v4.8-rc8","v4.8-rc2","v4.8-rc1","v4.8-rc7","v4.8-rc6","v4.8-rc5","v4.8-rc4","v4.8-rc3","v4.7","v4.7-rc4","v4.7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