It seems to be possible to craft a packet for sendmsg that triggers the -EFAULT path in skb_copy_bits resulting in a BUG_ON that looks like:
RIP: 0010:[<ffffffff817c6390>] [<ffffffff817c6390>] rawv6_sendmsg+0xc30/0xc40 RSP: 0018:ffff881f6c4a7c18 EFLAGS: 00010282 RAX: 00000000fffffff2 RBX: ffff881f6c681680 RCX: 0000000000000002 RDX: ffff881f6c4a7cf8 RSI: 0000000000000030 RDI: ffff881fed0f6a00 RBP: ffff881f6c4a7da8 R08: 0000000000000000 R09: 0000000000000009 R10: ffff881fed0f6a00 R11: 0000000000000009 R12: 0000000000000030 R13: ffff881fed0f6a00 R14: ffff881fee39ba00 R15: ffff881fefa93a80 Call Trace: [<ffffffff8118ba23>] ? unmap_page_range+0x693/0x830 [<ffffffff81772697>] inet_sendmsg+0x67/0xa0 [<ffffffff816d93f8>] sock_sendmsg+0x38/0x50 [<ffffffff816d982f>] SYSC_sendto+0xef/0x170 [<ffffffff816da27e>] SyS_sendto+0xe/0x10 [<ffffffff81002910>] do_syscall_64+0x50/0xa0 [<ffffffff817f7cbc>] entry_SYSCALL64_slow_path+0x25/0x25 Handle this in rawv6_push_pending_frames and jump to the failure path. Signed-off-by: Dave Jones <da...@codemonkey.org.uk> diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c index 291ebc260e70..35aa82faa052 100644 --- a/net/ipv6/raw.c +++ b/net/ipv6/raw.c @@ -591,7 +591,9 @@ static int rawv6_push_pending_frames(struct sock *sk, struct flowi6 *fl6, } offset += skb_transport_offset(skb); - BUG_ON(skb_copy_bits(skb, offset, &csum, 2)); + err = skb_copy_bits(skb, offset, &csum, 2); + if (err < 0) + goto out; /* in case cksum was not initialized */ if (unlikely(csum))