{"id":"CVE-2026-68462","summary":"bpf: Reject negative const offsets for buffer pointers","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject negative const offsets for buffer pointers\n\nThe verifier rejects variable offsets for PTR_TO_TP_BUFFER and PTR_TO_BUF\naccesses, but it currently accepts a constant negative offset produced by\npointer arithmetic.\n\nCommit 022ac0750883 (\"bpf: use reg-\u003evar_off instead of reg-\u003eoff for\npointers\") moved constant pointer offsets from reg-\u003eoff to reg-\u003evar_off.\nHowever, __check_buffer_access() continued to check only the instruction\noffset. An access with reg-\u003evar_off equal to -8 and an instruction offset\nof zero therefore passes verification.\n\nFor writable raw tracepoints, the access end is also calculated from the\nunsigned reg-\u003evar_off.value. An eight-byte access starting at -8 wraps\nthe calculated end to zero, allowing the program to load and attach\nwithout increasing max_tp_access.\n\nAfter ensuring that reg-\u003evar_off is constant, calculate the effective\naccess start using signed arithmetic and reject it when it is negative.\nUse the validated start to calculate the access end for both\nPTR_TO_TP_BUFFER and PTR_TO_BUF.","modified":"2026-08-16T03:48:27.811801129Z","published":"2026-08-15T05:51:21.948Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68462.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/314bd592085c0720ef519f6edbc5f41440ff78d4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/fd4cfa8c8f9a17cdec0539334d28754bc1d8a5d9"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68462.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-68462"},{"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":"022ac075088366b62e130da5e1b200bc93a47191"},{"fixed":"314bd592085c0720ef519f6edbc5f41440ff78d4"},{"fixed":"fd4cfa8c8f9a17cdec0539334d28754bc1d8a5d9"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-68462.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"7.1.0"},{"fixed":"7.1.5"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-68462.json"}}],"schema_version":"1.9.0"}