GHSA-5W87-22M9-4MHM
Vulnerability from github – Published: 2026-08-15 06:32 – Updated: 2026-08-17 06:33In the Linux kernel, the following vulnerability has been resolved:
bpf, sockmap: fix integer overflow in bpf_msg_pop_data() bounds check
start and len are u32, so
u64 last = start + len;
evaluates start + len in 32-bit and wraps before storing it in last. The bounds check
if (start >= offset + l || last > msg->sg.size)
return -EINVAL;
can then be passed with an out-of-range start/len, after which the pop loop runs off the end of the scatterlist and sk_msg_shift_left() calls put_page() on the empty msg->sg.end slot:
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] RIP: 0010:sk_msg_shift_left net/core/filter.c:2957 [inline] RIP: 0010:_bpfmsg_pop_data net/core/filter.c:3103 [inline] RIP: 0010:bpf_msg_pop_data+0x753/0x1a10 net/core/filter.c:2984 Call Trace: bpf_prog_4cc92c278f4d5d56+0x1b1/0x1e8 bpf_prog_run_pin_on_cpu+0x107/0x320 include/linux/filter.h:746 sk_psock_msg_verdict+0x357/0x7f0 net/core/skmsg.c:934 tcp_bpf_send_verdict net/ipv4/tcp_bpf.c:420 [inline] tcp_bpf_sendmsg+0x766/0x1ae0 net/ipv4/tcp_bpf.c:583 sock_sendmsg+0x153/0x1c0 net/socket.c:802 __sys_sendto+0x326/0x430 net/socket.c:2265 __x64_sys_sendto+0xe3/0x100 net/socket.c:2268 do_syscall_64+0x14c/0x480 entry_SYSCALL_64_after_hwframe+0x77/0x7f
Widen the addition with a (u64) cast so the bound is evaluated in 64-bit and a len near U32_MAX no longer wraps below msg->sg.size.
While here, change pop from int to u32. It counts bytes against the unsigned scatterlist lengths and can never be negative, so the signed type only invites sign-confusion in the pop loop.
{
"affected": [],
"aliases": [
"CVE-2026-74256"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-15T06:22:24Z",
"severity": "HIGH"
},
"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.",
"id": "GHSA-5w87-22m9-4mhm",
"modified": "2026-08-17T06:33:34Z",
"published": "2026-08-15T06:32:27Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74256"
},
{
"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"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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