From: Wei Wang <wei...@google.com> Sock hash only supports IPv4 socket proto right now. If a non-IPv4 socket gets stored in the BPF map, sk->sk_prot gets overwritten with the v4 tcp prot.
Syskaller reported the following related issue on an IPv6 socket: BUG: KASAN: slab-out-of-bounds in ip6_dst_idev include/net/ip6_fib.h:203 [inline] BUG: KASAN: slab-out-of-bounds in ip6_xmit+0x2002/0x23f0 net/ipv6/ip6_output.c:264 Read of size 8 at addr ffff8801b300edb0 by task syz-executor888/4522 CPU: 0 PID: 4522 Comm: syz-executor888 Not tainted 4.17.0-rc4+ #17 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1b9/0x294 lib/dump_stack.c:113 print_address_description+0x6c/0x20b mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 ip6_dst_idev include/net/ip6_fib.h:203 [inline] ip6_xmit+0x2002/0x23f0 net/ipv6/ip6_output.c:264 inet6_csk_xmit+0x377/0x630 net/ipv6/inet6_connection_sock.c:139 tcp_transmit_skb+0x1be0/0x3e40 net/ipv4/tcp_output.c:1159 tcp_send_syn_data net/ipv4/tcp_output.c:3441 [inline] tcp_connect+0x2207/0x45a0 net/ipv4/tcp_output.c:3480 tcp_v4_connect+0x1934/0x1d50 net/ipv4/tcp_ipv4.c:272 __inet_stream_connect+0x943/0x1120 net/ipv4/af_inet.c:655 tcp_sendmsg_fastopen net/ipv4/tcp.c:1162 [inline] tcp_sendmsg_locked+0x2859/0x3ee0 net/ipv4/tcp.c:1209 tcp_sendmsg+0x2f/0x50 net/ipv4/tcp.c:1447 inet_sendmsg+0x19f/0x690 net/ipv4/af_inet.c:798 sock_sendmsg_nosec net/socket.c:629 [inline] sock_sendmsg+0xd5/0x120 net/socket.c:639 ___sys_sendmsg+0x805/0x940 net/socket.c:2117 __sys_sendmsg+0x115/0x270 net/socket.c:2155 __do_sys_sendmsg net/socket.c:2164 [inline] __se_sys_sendmsg net/socket.c:2162 [inline] __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2162 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x43ff99 RSP: 002b:00007ffc00bd1cf8 EFLAGS: 00000217 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043ff99 RDX: 0000000020000000 RSI: 0000000020000580 RDI: 0000000000000003 RBP: 00000000006ca018 R08: 00000000004002c8 R09: 00000000004002c8 R10: 00000000004002c8 R11: 0000000000000217 R12: 00000000004018c0 R13: 0000000000401950 R14: 0000000000000000 R15: 0000000000000000 Fixes: 81110384441a ("bpf: sockmap, add hash map support") Reported-by: syzbot+5c063698bdbfac19f...@syzkaller.appspotmail.com Signed-off-by: Wei Wang <wei...@google.com> Acked-by: Eric Dumazet <eduma...@google.com> Acked-by: Willem de Bruijn <will...@google.com> --- kernel/bpf/sockmap.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c index 3b28955a6383..0e7b88bc3e3f 100644 --- a/kernel/bpf/sockmap.c +++ b/kernel/bpf/sockmap.c @@ -2300,6 +2300,11 @@ static int sock_hash_update_elem(struct bpf_map *map, return -EINVAL; } + if (skops.sk->sk_family != AF_INET) { + fput(socket->file); + return -EAFNOSUPPORT; + } + err = sock_hash_ctx_update_elem(&skops, map, key, flags); fput(socket->file); return err; -- 2.17.1.1185.g55be947832-goog