{"id":"CVE-2026-74256","summary":"bpf, sockmap: fix integer overflow in bpf_msg_pop_data() bounds check","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf, sockmap: fix integer overflow in bpf_msg_pop_data() bounds check\n\nstart and len are u32, so\n\n\tu64 last = start + len;\n\nevaluates start + len in 32-bit and wraps before storing it in last.\nThe bounds check\n\n\tif (start \u003e= offset + l || last \u003e msg-\u003esg.size)\n\t\treturn -EINVAL;\n\ncan then be passed with an out-of-range start/len, after which the pop\nloop runs off the end of the scatterlist and sk_msg_shift_left() calls\nput_page() on the empty msg-\u003esg.end slot:\n\n  Oops: general protection fault, probably for non-canonical address\n  0xdffffc0000000001: 0000 [#1] SMP KASAN PTI\n  KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]\n  RIP: 0010:sk_msg_shift_left net/core/filter.c:2957 [inline]\n  RIP: 0010:____bpf_msg_pop_data net/core/filter.c:3103 [inline]\n  RIP: 0010:bpf_msg_pop_data+0x753/0x1a10 net/core/filter.c:2984\n  Call Trace:\n   \u003cTASK\u003e\n   bpf_prog_4cc92c278f4d5d56+0x1b1/0x1e8\n   bpf_prog_run_pin_on_cpu+0x107/0x320 include/linux/filter.h:746\n   sk_psock_msg_verdict+0x357/0x7f0 net/core/skmsg.c:934\n   tcp_bpf_send_verdict net/ipv4/tcp_bpf.c:420 [inline]\n   tcp_bpf_sendmsg+0x766/0x1ae0 net/ipv4/tcp_bpf.c:583\n   __sock_sendmsg+0x153/0x1c0 net/socket.c:802\n   __sys_sendto+0x326/0x430 net/socket.c:2265\n   __x64_sys_sendto+0xe3/0x100 net/socket.c:2268\n   do_syscall_64+0x14c/0x480\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\n   \u003c/TASK\u003e\n\nWiden the addition with a (u64) cast so the bound is evaluated in\n64-bit and a len near U32_MAX no longer wraps below msg-\u003esg.size.\n\nWhile here, change pop from int to u32. It counts bytes against the\nunsigned scatterlist lengths and can never be negative, so the signed\ntype only invites sign-confusion in the pop loop.","modified":"2026-08-18T03:56:45.079882624Z","published":"2026-08-15T05:57:34.956Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74256.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/17eb9832a10db2f7a80cb429ca2bc5038445a943"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9ef44ed6fb0c1db01cfcc3de432a33e719713eb5"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a48802fb2cd2d1e23651989f8ff4d15e9d5dad54"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ba5cc05dae8fce237d191c7ea96b1107a791e548"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c05a0ec1cdced622a1a0c7d85679fe02f31033ec"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d693c5ed67dabe1ccbf8dcea93075bdc9ffd4ca0"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e09f7bd7273928b4089e6b71f8e992f2b356ca1b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/fe09dd288722f1c749b7506c0b3e7841a7d85027"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74256.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74256"},{"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":"7246d8ed4dcce23f7509949a77be15fa9f0e3d28"},{"fixed":"9ef44ed6fb0c1db01cfcc3de432a33e719713eb5"},{"fixed":"d693c5ed67dabe1ccbf8dcea93075bdc9ffd4ca0"},{"fixed":"ba5cc05dae8fce237d191c7ea96b1107a791e548"},{"fixed":"c05a0ec1cdced622a1a0c7d85679fe02f31033ec"},{"fixed":"17eb9832a10db2f7a80cb429ca2bc5038445a943"},{"fixed":"fe09dd288722f1c749b7506c0b3e7841a7d85027"},{"fixed":"e09f7bd7273928b4089e6b71f8e992f2b356ca1b"},{"fixed":"a48802fb2cd2d1e23651989f8ff4d15e9d5dad54"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74256.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.0.0"},{"fixed":"5.10.261"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.212"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.178"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.145"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.97"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.40"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.5"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74256.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}