CVE-2026-43164

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

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

syzbot reported null-ptr-deref of udpsk(sk)->udpprod_queue. [0]

Since the cited commit, udplibinitsock() can fail, as can udpinitsock() and udpv6init_sock().

Let's handle the error in udpliteskinit() and udplitev6skinit().

BUG: KASAN: null-ptr-deref in atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline] BUG: KASAN: null-ptr-deref in _udpenqueuescheduleskb+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> dumpstacklvl+0xe8/0x150 lib/dumpstack.c:120 kasanreport+0xa2/0xe0 mm/kasan/report.c:595 checkregioninline mm/kasan/generic.c:-1 [inline] kasancheckrange+0x264/0x2c0 mm/kasan/generic.c:200 instrumentatomicread include/linux/instrumented.h:82 [inline] atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline] __udpenqueueschedule_skb+0x151/0x1480 net/ipv4/udp.c:1719 __udpv6queuercvskb net/ipv6/udp.c:795 [inline] udpv6queuercvoneskb+0xa2e/0x1ad0 net/ipv6/udp.c:906 udp6unicastrcvskb+0x227/0x380 net/ipv6/udp.c:1064 ip6protocoldeliverrcu+0xe17/0x1540 net/ipv6/ip6input.c:438 ip6inputfinish+0x191/0x350 net/ipv6/ip6input.c:489 NFHOOK+0x354/0x3f0 include/linux/netfilter.h:318 ip6input+0x16c/0x2b0 net/ipv6/ip6input.c:500 NF_HOOK+0x354/0x3f0 include/linux/netfilter.h:318 __netifreceiveskbonecore net/core/dev.c:6149 [inline] __netifreceiveskb+0xd3/0x370 net/core/dev.c:6262 process_backlog+0x4d6/0x1160 net/core/dev.c:6614 __napipoll+0xae/0x320 net/core/dev.c:7678 napipoll net/core/dev.c:7741 [inline] netrxaction+0x60d/0xdc0 net/core/dev.c:7893 handlesoftirqs+0x209/0x8d0 kernel/softirq.c:622 dosoftirq+0x52/0x90 kernel/softirq.c:523 </IRQ> <TASK> __localbhenableip+0xe7/0x120 kernel/softirq.c:450 localbhenable include/linux/bottomhalf.h:33 [inline] rcureadunlock_bh include/linux/rcupdate.h:924 [inline] __devqueuexmit+0x109c/0x2dc0 net/core/dev.c:4856 __ip6finishoutput net/ipv6/ip6output.c:-1 [inline] ip6finish_output+0x158/0x4e0 net/ipv6/ip6output.c:219 NFHOOKCOND include/linux/netfilter.h:307 [inline] ip6output+0x342/0x580 net/ipv6/ip6output.c:246 ip6sendskb+0x1d7/0x3c0 net/ipv6/ip6output.c:1984 udpv6sendskb+0x9a5/0x1770 net/ipv6/udp.c:1442 udpv6pushpendingframes+0xa2/0x140 net/ipv6/udp.c:1469 udpv6sendmsg+0xfe0/0x2830 net/ipv6/udp.c:1759 socksendmsgnosec net/socket.c:727 [inline] __sock_sendmsg+0xe5/0x270 net/socket.c:742 __sys_sendto+0x3eb/0x580 net/socket.c:2206 __dosyssendto net/socket.c:2213 [inline] __sesyssendto net/socket.c:2209 [inline] _x64syssendto+0xde/0x100 net/socket.c:2209 dosyscallx64 arch/x86/entry/syscall64.c:63 [inline] dosyscall64+0xd2/0xf20 arch/x86/entry/syscall64.c:94 entrySYSCALL64afterhwframe+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 ORIGRAX: 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>