diff options
| author | Eric Dumazet <edumazet@google.com> | 2016-10-12 19:01:45 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-10-13 11:07:34 -0400 |
| commit | 8ce48623f0cf3d632e32448411feddccb693d351 (patch) | |
| tree | a80202e9a7f07d6cc2d640312ce0377fadb18701 /net/ipv6 | |
| parent | 3f2b0a5a3583a2c6c3aeb2d59e7f775d43faa89c (diff) | |
ipv6: tcp: restore IP6CB for pktoptions skbs
Baozeng Ding reported following KASAN splat :
BUG: KASAN: use-after-free in ip6_datagram_recv_specific_ctl+0x13f1/0x15c0 at addr ffff880029c84ec8
Read of size 1 by task poc/25548
Call Trace:
[<ffffffff82cf43c9>] dump_stack+0x12e/0x185 /lib/dump_stack.c:15
[< inline >] print_address_description /mm/kasan/report.c:204
[<ffffffff817ced3b>] kasan_report_error+0x48b/0x4b0 /mm/kasan/report.c:283
[< inline >] kasan_report /mm/kasan/report.c:303
[<ffffffff817ced9e>] __asan_report_load1_noabort+0x3e/0x40 /mm/kasan/report.c:321
[<ffffffff85c71da1>] ip6_datagram_recv_specific_ctl+0x13f1/0x15c0 /net/ipv6/datagram.c:687
[<ffffffff85c734c3>] ip6_datagram_recv_ctl+0x33/0x40
[<ffffffff85c0b07c>] do_ipv6_getsockopt.isra.4+0xaec/0x2150
[<ffffffff85c0c7f6>] ipv6_getsockopt+0x116/0x230
[<ffffffff859b5a12>] tcp_getsockopt+0x82/0xd0 /net/ipv4/tcp.c:3035
[<ffffffff855fb385>] sock_common_getsockopt+0x95/0xd0 /net/core/sock.c:2647
[< inline >] SYSC_getsockopt /net/socket.c:1776
[<ffffffff855f8ba2>] SyS_getsockopt+0x142/0x230 /net/socket.c:1758
[<ffffffff8685cdc5>] entry_SYSCALL_64_fastpath+0x23/0xc6
Memory state around the buggy address:
ffff880029c84d80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff880029c84e00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> ffff880029c84e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff880029c84f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff880029c84f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
He also provided a syzkaller reproducer.
Issue is that ip6_datagram_recv_specific_ctl() expects to find IP6CB
data that was moved at a different place in tcp_v6_rcv()
This patch moves tcp_v6_restore_cb() up and calls it from
tcp_v6_do_rcv() when np->pktoptions is set.
Fixes: 971f10eca186 ("tcp: better TCP_SKB_CB layout to reduce cache line misses")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Baozeng Ding <sploving1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6')
| -rw-r--r-- | net/ipv6/tcp_ipv6.c | 20 |
1 files changed, 11 insertions, 9 deletions
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 54cf7197c7ab..5a27ab4eab39 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1190,6 +1190,16 @@ out: return NULL; } +static void tcp_v6_restore_cb(struct sk_buff *skb) +{ + /* We need to move header back to the beginning if xfrm6_policy_check() + * and tcp_v6_fill_cb() are going to be called again. + * ip6_datagram_recv_specific_ctl() also expects IP6CB to be there. + */ + memmove(IP6CB(skb), &TCP_SKB_CB(skb)->header.h6, + sizeof(struct inet6_skb_parm)); +} + /* The socket must have it's spinlock held when we get * here, unless it is a TCP_LISTEN socket. * @@ -1319,6 +1329,7 @@ ipv6_pktoptions: np->flow_label = ip6_flowlabel(ipv6_hdr(opt_skb)); if (ipv6_opt_accepted(sk, opt_skb, &TCP_SKB_CB(opt_skb)->header.h6)) { skb_set_owner_r(opt_skb, sk); + tcp_v6_restore_cb(opt_skb); opt_skb = xchg(&np->pktoptions, opt_skb); } else { __kfree_skb(opt_skb); @@ -1352,15 +1363,6 @@ static void tcp_v6_fill_cb(struct sk_buff *skb, const struct ipv6hdr *hdr, TCP_SKB_CB(skb)->sacked = 0; } -static void tcp_v6_restore_cb(struct sk_buff *skb) -{ - /* We need to move header back to the beginning if xfrm6_policy_check() - * and tcp_v6_fill_cb() are going to be called again. - */ - memmove(IP6CB(skb), &TCP_SKB_CB(skb)->header.h6, - sizeof(struct inet6_skb_parm)); -} - static int tcp_v6_rcv(struct sk_buff *skb) { const struct tcphdr *th; |