CVE-2026-43164

In the Linux kernel, the following vulnerability has been resolved:

udplite: Fix null-ptr-deref in __udp_enqueue_schedule_skb().

syzbot reported null-ptr-deref of udp_sk(sk)->udp_prod_queue. [0]

Since the cited commit, udp_lib_init_sock() can fail, as can

udp_init_sock() and udpv6_init_sock().

Let's handle the error in udplite_sk_init() and udplitev6_sk_init().

[0]:

BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:82 [inline]

BUG: KASAN: null-ptr-deref in atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline]

BUG: KASAN: null-ptr-deref in __udp_enqueue_schedule_skb+0x151/0x1480 net/ipv4/udp.c:1719

Read of size 4 at addr 0000000000000008 by task syz.2.18/2944

CPU: 1 UID: 0 PID: 2944 Comm: syz.2.18 Not tainted syzkaller #0 PREEMPTLAZY

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025

Call Trace:

<IRQ>

dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120

kasan_report+0xa2/0xe0 mm/kasan/report.c:595

check_region_inline mm/kasan/generic.c:-1 [inline]

kasan_check_range+0x264/0x2c0 mm/kasan/generic.c:200

instrument_atomic_read include/linux/instrumented.h:82 [inline]

atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline]

__udp_enqueue_schedule_skb+0x151/0x1480 net/ipv4/udp.c:1719

__udpv6_queue_rcv_skb net/ipv6/udp.c:795 [inline]

udpv6_queue_rcv_one_skb+0xa2e/0x1ad0 net/ipv6/udp.c:906

udp6_unicast_rcv_skb+0x227/0x380 net/ipv6/udp.c:1064

ip6_protocol_deliver_rcu+0xe17/0x1540 net/ipv6/ip6_input.c:438

ip6_input_finish+0x191/0x350 net/ipv6/ip6_input.c:489

NF_HOOK+0x354/0x3f0 include/linux/netfilter.h:318

ip6_input+0x16c/0x2b0 net/ipv6/ip6_input.c:500

NF_HOOK+0x354/0x3f0 include/linux/netfilter.h:318

__netif_receive_skb_one_core net/core/dev.c:6149 [inline]

__netif_receive_skb+0xd3/0x370 net/core/dev.c:6262

process_backlog+0x4d6/0x1160 net/core/dev.c:6614

__napi_poll+0xae/0x320 net/core/dev.c:7678

napi_poll net/core/dev.c:7741 [inline]

net_rx_action+0x60d/0xdc0 net/core/dev.c:7893

handle_softirqs+0x209/0x8d0 kernel/softirq.c:622

do_softirq+0x52/0x90 kernel/softirq.c:523

</IRQ>

<TASK>

__local_bh_enable_ip+0xe7/0x120 kernel/softirq.c:450

local_bh_enable include/linux/bottom_half.h:33 [inline]

rcu_read_unlock_bh include/linux/rcupdate.h:924 [inline]

__dev_queue_xmit+0x109c/0x2dc0 net/core/dev.c:4856

__ip6_finish_output net/ipv6/ip6_output.c:-1 [inline]

ip6_finish_output+0x158/0x4e0 net/ipv6/ip6_output.c:219

NF_HOOK_COND include/linux/netfilter.h:307 [inline]

ip6_output+0x342/0x580 net/ipv6/ip6_output.c:246

ip6_send_skb+0x1d7/0x3c0 net/ipv6/ip6_output.c:1984

udp_v6_send_skb+0x9a5/0x1770 net/ipv6/udp.c:1442

udp_v6_push_pending_frames+0xa2/0x140 net/ipv6/udp.c:1469

udpv6_sendmsg+0xfe0/0x2830 net/ipv6/udp.c:1759

sock_sendmsg_nosec net/socket.c:727 [inline]

__sock_sendmsg+0xe5/0x270 net/socket.c:742

__sys_sendto+0x3eb/0x580 net/socket.c:2206

__do_sys_sendto net/socket.c:2213 [inline]

__se_sys_sendto net/socket.c:2209 [inline]

__x64_sys_sendto+0xde/0x100 net/socket.c:2209

do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]

do_syscall_64+0xd2/0xf20 arch/x86/entry/syscall_64.c:94

entry_SYSCALL_64_after_hwframe+0x76/0x7e

RIP: 0033:0x7f67b4d9c629

Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48

RSP: 002b:00007f67b5c98028 EFLAGS: 00000246 ORIG_RAX: 000000000000002c

RAX: ffffffffffffffda RBX: 00007f67b5015fa0 RCX: 00007f67b4d9c629

RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003

RBP: 00007f67b4e32b39 R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000040000 R11: 0000000000000246 R12: 0000000000000000

R13: 00007f67b5016038 R14: 00007f67b5015fa0 R15: 00007ffe3cb66dd8

</TASK>