{"id":"CVE-2026-98647","title":"bpf: Fix divide-by-zero in btf_struct_walk()","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix divide-by-zero in btf_struct_walk()\n\nWhen an access goes past the struct and the last member is a flexible\narray, btf_struct_walk() folds the offset back into …","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 9c5f8a1008a121e4c6b24af211034e24b0b63081 < 1ea3820937f8022e044c41c6e95c84b02741b45f","Linux >= 9c5f8a1008a121e4c6b24af211034e24b0b63081 < 172756f02663ad45c889c001c1a8cb4082a01a05","Linux >= 9c5f8a1008a121e4c6b24af211034e24b0b63081 < 934e9ba9f8d05656a48624710be67ca4dc8482e6","Linux >= 9c5f8a1008a121e4c6b24af211034e24b0b63081 < 63af086cb5fa6f72fd924f86bea4c2194da663a2","Linux >= 9c5f8a1008a121e4c6b24af211034e24b0b63081 < 8eb4cd72daad3a9ee63d2281bbdd16ce6d9406b1","Linux >= 9c5f8a1008a121e4c6b24af211034e24b0b63081 < b8fa56722e9c43bcd59c51fe4c7edd5f4158a11b","Linux >= 9c5f8a1008a121e4c6b24af211034e24b0b63081 < b0b3dc66529676228cb938cbcad66920f735c223","Linux 5.8"],"published":"2026-10-18","updated":"2026-10-19","sourceUpdated":"2026-10-19T09:23:16.870Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98647","references":[{"url":"https://git.kernel.org/stable/c/1ea3820937f8022e044c41c6e95c84b02741b45f"},{"url":"https://git.kernel.org/stable/c/172756f02663ad45c889c001c1a8cb4082a01a05"},{"url":"https://git.kernel.org/stable/c/934e9ba9f8d05656a48624710be67ca4dc8482e6"},{"url":"https://git.kernel.org/stable/c/63af086cb5fa6f72fd924f86bea4c2194da663a2"},{"url":"https://git.kernel.org/stable/c/8eb4cd72daad3a9ee63d2281bbdd16ce6d9406b1"},{"url":"https://git.kernel.org/stable/c/b8fa56722e9c43bcd59c51fe4c7edd5f4158a11b"},{"url":"https://git.kernel.org/stable/c/b0b3dc66529676228cb938cbcad66920f735c223"}],"tags":["cve.org"],"ingestedAt":"2026-10-18T15:45:12.229Z","slug":"CVE-2026-98647","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix divide-by-zero in btf_struct_walk()\n\nWhen an access goes past the struct and the last member is a flexible\narray, btf_struct_walk() folds the offset back into a single element with\n(off - moff) % t->size, but never checks that the element type has a size.\n\nBTF takes an empty struct, so this in program BTF\n\n\t/* event could be empty */\n\tstruct event {\n #ifdef HAVE_TIMESTAMP\n\t\t__u64 ts;\n #endif\n\t};\n\n\tstruct batch {\n\t\tint nr;\n\t\tstruct event events[];\n\t};\n\ndivides by zero at prog load time. Getting there needs a PTR_TO_BTF_ID that\nis not MEM_ALLOC, e.g. a plain read of a local kptr stashed in a map from a\nsleepable program.\n\nOops: divide error: 0000 [#1] SMP KASAN PTI\nRIP: 0010:btf_struct_walk+0x53f/0x1570\nCall Trace:\n <TASK>\n btf_struct_access+0x42a/0xcd0\n check_ptr_to_btf_access+0x4dc/0x1160\n check_mem_access+0x3a45/0x8740\n check_load_mem+0x36a/0xd10\n do_check_common+0x3ef0/0xb210\n bpf_check+0x6d3b/0x8580\n bpf_prog_load+0xf7c/0x2720\n __sys_bpf+0xa83/0x3690\n __x64_sys_bpf+0xc7/0x150\n x64_sys_call+0x1f3f/0x27e0\n do_syscall_64+0xe5/0x610\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n </TASK>\n\nReject a zero-sized element type. The fixed array path in the same function\nalready bails out on the same thing:\n\n\tbtf_struct_walk()\n\t...\n\t\t/* skip empty array */\n\t\tif (moff == mtrue_end)\n\t\t\tcontinue;\n\n\t\tmsize /= total_nelems;\n\n## Affected\n\n- `Linux >= 9c5f8a1008a121e4c6b24af211034e24b0b63081 < 1ea3820937f8022e044c41c6e95c84b02741b45f`\n- `Linux >= 9c5f8a1008a121e4c6b24af211034e24b0b63081 < 172756f02663ad45c889c001c1a8cb4082a01a05`\n- `Linux >= 9c5f8a1008a121e4c6b24af211034e24b0b63081 < 934e9ba9f8d05656a48624710be67ca4dc8482e6`\n- `Linux >= 9c5f8a1008a121e4c6b24af211034e24b0b63081 < 63af086cb5fa6f72fd924f86bea4c2194da663a2`\n- `Linux >= 9c5f8a1008a121e4c6b24af211034e24b0b63081 < 8eb4cd72daad3a9ee63d2281bbdd16ce6d9406b1`\n- `Linux >= 9c5f8a1008a121e4c6b24af211034e24b0b63081 < b8fa56722e9c43bcd59c51fe4c7edd5f4158a11b`\n- `Linux >= 9c5f8a1008a121e4c6b24af211034e24b0b63081 < b0b3dc66529676228cb938cbcad66920f735c223`\n- `Linux 5.8`\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":[]}