From: Ziyang Xuan william.xuanziyang@huawei.com
[ Upstream commit ea30388baebcce37fd594d425a65037ca35e59e8 ]
Syzbot reported a bug as following:
===================================================== BUG: KMSAN: uninit-value in arch_atomic64_inc arch/x86/include/asm/atomic64_64.h:88 [inline] BUG: KMSAN: uninit-value in arch_atomic_long_inc include/linux/atomic/atomic-long.h:161 [inline] BUG: KMSAN: uninit-value in atomic_long_inc include/linux/atomic/atomic-instrumented.h:1429 [inline] BUG: KMSAN: uninit-value in __ip6_make_skb+0x2f37/0x30f0 net/ipv6/ip6_output.c:1956 arch_atomic64_inc arch/x86/include/asm/atomic64_64.h:88 [inline] arch_atomic_long_inc include/linux/atomic/atomic-long.h:161 [inline] atomic_long_inc include/linux/atomic/atomic-instrumented.h:1429 [inline] __ip6_make_skb+0x2f37/0x30f0 net/ipv6/ip6_output.c:1956 ip6_finish_skb include/net/ipv6.h:1122 [inline] ip6_push_pending_frames+0x10e/0x550 net/ipv6/ip6_output.c:1987 rawv6_push_pending_frames+0xb12/0xb90 net/ipv6/raw.c:579 rawv6_sendmsg+0x297e/0x2e60 net/ipv6/raw.c:922 inet_sendmsg+0x101/0x180 net/ipv4/af_inet.c:827 sock_sendmsg_nosec net/socket.c:714 [inline] sock_sendmsg net/socket.c:734 [inline] ____sys_sendmsg+0xa8e/0xe70 net/socket.c:2476 ___sys_sendmsg+0x2a1/0x3f0 net/socket.c:2530 __sys_sendmsg net/socket.c:2559 [inline] __do_sys_sendmsg net/socket.c:2568 [inline] __se_sys_sendmsg net/socket.c:2566 [inline] __x64_sys_sendmsg+0x367/0x540 net/socket.c:2566 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd
Uninit was created at: slab_post_alloc_hook mm/slab.h:766 [inline] slab_alloc_node mm/slub.c:3452 [inline] __kmem_cache_alloc_node+0x71f/0xce0 mm/slub.c:3491 __do_kmalloc_node mm/slab_common.c:967 [inline] __kmalloc_node_track_caller+0x114/0x3b0 mm/slab_common.c:988 kmalloc_reserve net/core/skbuff.c:492 [inline] __alloc_skb+0x3af/0x8f0 net/core/skbuff.c:565 alloc_skb include/linux/skbuff.h:1270 [inline] __ip6_append_data+0x51c1/0x6bb0 net/ipv6/ip6_output.c:1684 ip6_append_data+0x411/0x580 net/ipv6/ip6_output.c:1854 rawv6_sendmsg+0x2882/0x2e60 net/ipv6/raw.c:915 inet_sendmsg+0x101/0x180 net/ipv4/af_inet.c:827 sock_sendmsg_nosec net/socket.c:714 [inline] sock_sendmsg net/socket.c:734 [inline] ____sys_sendmsg+0xa8e/0xe70 net/socket.c:2476 ___sys_sendmsg+0x2a1/0x3f0 net/socket.c:2530 __sys_sendmsg net/socket.c:2559 [inline] __do_sys_sendmsg net/socket.c:2568 [inline] __se_sys_sendmsg net/socket.c:2566 [inline] __x64_sys_sendmsg+0x367/0x540 net/socket.c:2566 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd
It is because icmp6hdr does not in skb linear region under the scenario of SOCK_RAW socket. Access icmp6_hdr(skb)->icmp6_type directly will trigger the uninit variable access bug.
Use a local variable icmp6_type to carry the correct value in different scenarios.
Fixes: 14878f75abd5 ("[IPV6]: Add ICMPMsgStats MIB (RFC 4293) [rev 2]") Reported-by: syzbot+8257f4dcef79de670baf@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?id=3d605ec1d0a7f2a269a1a6936ac7f2b85975ee9... Signed-off-by: Ziyang Xuan william.xuanziyang@huawei.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv6/ip6_output.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index e427f5040a08e..c62e44224bf84 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -1925,8 +1925,13 @@ struct sk_buff *__ip6_make_skb(struct sock *sk, IP6_UPD_PO_STATS(net, rt->rt6i_idev, IPSTATS_MIB_OUT, skb->len); if (proto == IPPROTO_ICMPV6) { struct inet6_dev *idev = ip6_dst_idev(skb_dst(skb)); + u8 icmp6_type;
- ICMP6MSGOUT_INC_STATS(net, idev, icmp6_hdr(skb)->icmp6_type); + if (sk->sk_socket->type == SOCK_RAW && !inet_sk(sk)->hdrincl) + icmp6_type = fl6->fl6_icmp_type; + else + icmp6_type = icmp6_hdr(skb)->icmp6_type; + ICMP6MSGOUT_INC_STATS(net, idev, icmp6_type); ICMP6_INC_STATS(net, idev, ICMP6_MIB_OUTMSGS); }