{"id":"CVE-2026-98049","revision":"3facf89c81344933961863051b84e425","records":[{"revision":"3facf89c81344933961863051b84e425","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-98049","aliases":[],"title":"bpf: zero extend the result of an arena 32-bit cmpxchg","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: zero extend the result of an arena 32-bit cmpxchg\n\nbpf_convert_ctx_accesses() rewrites an atomic on an arena pointer from\nBPF_STX | BPF_ATOMIC to BPF_STX | BPF_PROBE_ATOMIC, and it runs before\nbpf_opt_subreg_zext_lo32_rnd_hi32().\n\nThat pass emits an explicit zero extension for a 32-bit cmpxchg even\nwhen bpf_jit_needs_zext() is false. This is done because on some\narchitectures 32-bit cmpxchg requires explicit zero extension for the\ndst register. E.g. on x86-64 'lock cmpxchg' does not change the %eax\nif comparison is successful, while BPF semantics declare that each\noperation on a 32-bit register zero extends it's upper half.\n\nis_cmpxchg_insn() matches BPF_MODE == BPF_ATOMIC only, so an arena\ncmpxchg misses said zero extension adjustment. This patch adjusts\nis_cmpxchg_insn() to match BPF_PROBE_ATOMIC alongside BPF_ATOMIC.","state":0,"publishedAt":"2026-09-25T10:23:58.561+00:00","modifiedAt":"2026-10-21T12:54:16.141+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"kernel/bpf/fixups.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"d503a04f8bc0c75dc9db9452d8cc79d748afb752\",\n                            \"lessThan\": \"1bb1be18263995b159cf5afad3a05500ba6d2a7b\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"d503a04f8bc0c75dc9db9452d8cc79d748afb752\",\n                            \"lessThan\": \"6bb6ae5ab1beffda51dabf41612f501d07f10fc6\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"d503a04f8bc0c75dc9db9452d8cc79d748afb752\",\n                            \"lessThan\": \"1c1b476d43a8b6c9bc04600369dd8cc39950d98e\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"d503a04f8bc0c75dc9db9452d8cc79d748afb752\",\n                            \"lessThan\": \"4814ed6406f3493bd554ad046da5f7fc04833571\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"kernel/bpf/fixups.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"6.10\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"6.10\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.114\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.57\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2.7\",\n                            \"lessThanOrEqual\": \"7.2.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.3\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[],"references":["https://git.kernel.org/stable/c/1bb1be18263995b159cf5afad3a05500ba6d2a7b","https://git.kernel.org/stable/c/6bb6ae5ab1beffda51dabf41612f501d07f10fc6","https://git.kernel.org/stable/c/1c1b476d43a8b6c9bc04600369dd8cc39950d98e","https://git.kernel.org/stable/c/4814ed6406f3493bd554ad046da5f7fc04833571"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98049","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-98049","identifiers":["CVE-2026-98049"]},"retained":false,"historicalAffected":[]}],"coverage":[]}