The dev pointer can be NULL in dev_hard_header(). Add check for dev being NULL in dev_hard_header() to avoid GPF. general protection fault, probably for non-canonical address 0xdffffc0000000046: 0000 [#1] PREEMPT SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000230-0x0000000000000237] CPU: 1 PID: 45 Comm: kworker/1:1 Not tainted 6.1.0-rc7+ #2 Hardware name: Red Hat KVM, BIOS 1.15.0-2.module+el8.6.0+20659+3dcf7c70 Workqueue: mld mld_ifc_work RIP: 0010:macvlan_hard_header (./include/linux/netdevice.h:3057 (discriminator 4) drivers/net/macvlan.c:594 (discriminator 4)) RSP: 0018:ffff888103d377d0 EFLAGS: 00010212 RAX: dffffc0000000000 RBX: ffff88801cf1a000 RCX: 0000000000000000 RDX: 0000000000000046 RSI: 0000000000000000 RDI: 0000000000000230 RBP: ffff88801e8ef328 R08: 0000000000000000 R09: 0000000000000060 R10: 0000000000000000 R11: 0000000000000000 R12: ffff88801f0497c0 R13: 0000000000000000 R14: ffff888045187c98 R15: 0000000000000060 FS: 0000000000000000(0000) GS:ffff888106c80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fbf3f1c1840 CR3: 0000000014e36000 CR4: 00000000000006e0 Call Trace: <TASK> neigh_connected_output (./include/linux/netdevice.h:3060 net/core/neighbour.c:1595) ip6_finish_output2 (./include/net/neighbour.h:546 net/ipv6/ip6_output.c:134) ip6_finish_output (net/ipv6/ip6_output.c:195 net/ipv6/ip6_output.c:206) ip6_output (./include/linux/netfilter.h:291 net/ipv6/ip6_output.c:227) NF_HOOK.constprop.0 (./include/net/dst.h:445 ./include/linux/netfilter.h:302) mld_sendpack (net/ipv6/mcast.c:1824) mld_send_cr (net/ipv6/mcast.c:2122) mld_ifc_work (net/ipv6/mcast.c:2655) process_one_work (kernel/workqueue.c:2294) worker_thread (./include/linux/list.h:292 kernel/workqueue.c:2437) kthread (kernel/kthread.c:376) ret_from_fork (arch/x86/entry/entry_64.S:312) </TASK> Modules linked in: Dumping ftrace buffer: (ftrace buffer empty) ---[ end trace 0000000000000000 ]--- Fixes: 0c4e85813d0a ("[NET]: Wrap netdevice hardware header creation.") Reported-by: syzkaller <syzkaller@xxxxxxxxxxxxxxxx> Signed-off-by: George Kennedy <george.kennedy@xxxxxxxxxx> --- include/linux/netdevice.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index eddf8ee270e7..9b25a6301fa5 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -3054,7 +3054,7 @@ static inline int dev_hard_header(struct sk_buff *skb, struct net_device *dev, const void *daddr, const void *saddr, unsigned int len) { - if (!dev->header_ops || !dev->header_ops->create) + if (!dev || !dev->header_ops || !dev->header_ops->create) return 0; return dev->header_ops->create(skb, dev, type, daddr, saddr, len); -- 2.31.1