CVE-2026-74256

Status: UPDATED  |  Advisory ID: CVE-2026-74256

Key Details

Affected Products, Subsystems & Sectors

What to Know

In 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:____bpf_msg_pop_data net/core/filter.c:3103 [inline]

RIP: 0010:bpf_msg_pop_data+0x753/0x1a10 net/core/filter.c:2984

Call Trace:

<TASK>

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

</TASK>

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. (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References