{"id":"CVE-2026-98043","summary":"bpf: Don't infer non-NULL from a pointer with an unbounded offset","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Don't infer non-NULL from a pointer with an unbounded offset\n\nreg_not_null() decides that a register holds a non-NULL value by\nlooking at its type alone. For pointer types that allow arithmetic the\ntype only guarantees a non-NULL base, in case of an unbound offset\nthe runtime offset value might still add up to NULL.\nConsider the followng program:\n\n  r6 = bpf_map_lookup_elem(map, &0);  /* present */\n  if (r6 == 0) return 0;\n  r7 = bpf_map_lookup_elem(map, &1);  /* absent, NULL at runtime */\n  r8 = r7;\n  r8 -= r6;     /* pointer - pointer: unknown scalar, -r6 */\n  r8 \u003c\u003c= 1;\n  r8 \u003e\u003e= 1;     /* any non-negative offset is accepted by */\n                /* check_reg_sane_offset_ptr() */\n  r6 += r8;     /* verifier: map value;    runtime: zero  */\n  if (r7 != r6) return 0;\n  *(u8 *)(r7 + 0);  /* r7 is inferred non-NULL, both are zero */\n\nAt runtime both registers are zero, the comparison is true and the\nload faults with NULL pointer dereference.\n\nRequire the offset to be within +-BPF_MAX_VAR_OFF in reg_not_null().","modified":"2026-09-26T03:48:31.881645829Z","published":"2026-09-25T10:23:54.865Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98043.json"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/67b529f521a6676cdfc78b91b0217d7eaa84216b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cb6642048739bf4ee5aa09fe465511f1e87caa63"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98043.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98043"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"cac616db39c207dc63465a4e05c6ce0e60b2cce4"},{"fixed":"cb6642048739bf4ee5aa09fe465511f1e87caa63"},{"fixed":"67b529f521a6676cdfc78b91b0217d7eaa84216b"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98043.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.8.0"},{"fixed":"7.2.7"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98043.json"}}],"schema_version":"1.9.0"}