{"id":"CVE-2026-90211","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf, s390: Clear fetch destination on faulting arena atomic\n\nSame missing register clear as on riscv64","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf, s390: Clear fetch destination on faulting arena atomic\n\nSame missing register clear as on riscv64. A RMW atomic on an arena pointer\nis converted to BPF_PROBE_ATOMI…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 2f9469484a3b52c66b799de73bd1ca75617bc8d5 < 1a26541b3f60ce447433a4c4dd56edb10d2cd580","Linux >= 2f9469484a3b52c66b799de73bd1ca75617bc8d5 < 44b702fceb4cf3a4ddbfb496f487b034814bf1a3","Linux >= 2f9469484a3b52c66b799de73bd1ca75617bc8d5 < cc3e12330599f097f0e1f792435686ddc276f26d","Linux 6.11"],"published":"2026-09-17","updated":"2026-09-21","sourceUpdated":"2026-09-21T14:17:28.800","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-90211","references":[{"url":"https://git.kernel.org/stable/c/44b702fceb4cf3a4ddbfb496f487b034814bf1a3","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/cc3e12330599f097f0e1f792435686ddc276f26d","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/1a26541b3f60ce447433a4c4dd56edb10d2cd580","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd","cve.org"],"epss":0.00189,"epssPercentile":0.08844,"ingestedAt":"2026-09-17T16:21:47.858Z","slug":"CVE-2026-90211","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nbpf, s390: Clear fetch destination on faulting arena atomic\n\nSame missing register clear as on riscv64. A RMW atomic on an arena pointer\nis converted to BPF_PROBE_ATOMIC and gets an exception table entry, but\nbpf_jit_probe_atomic_pre() only fills in the arena base and the probe\noffset, leaving probe->reg at the -1 that bpf_jit_probe_init() set, which\nbpf_jit_probe_post() writes into the entry and ex_handler_bpf() then reads\nback as \"there is nothing to clear\".\n\nThat is right for a plain BPF_{ADD,AND,OR,XOR}, which only writes memory,\nbut an RMW carrying BPF_FETCH also reads the old value into a register:\nsrc_reg for BPF_{ADD,AND,OR,XOR} | BPF_FETCH and BPF_XCHG, and r0 for\nBPF_CMPXCHG. So on a fault over an unmapped arena page the program resumes\nat the landing pad with whatever that register held before the atomic\ninstead of the 0 that every other BPF_PROBE_* access delivers.\n\nFill probe->reg in from bpf_atomic_load_reg(). Unlike x86-64 and arm64,\ns390x does not report arena violations from its exception handler, so there\nis no access direction to correct here, only the missing register clear.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}