aboutsummaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorChristoph Paasch <cpaasch@apple.com>2019-03-11 11:41:05 -0700
committerDavid S. Miller <davem@davemloft.net>2019-03-11 15:36:49 -0700
commitf2feaefdabb0a6253aa020f65e7388f07a9ed47c (patch)
treed79b2b98513771ba6e4460a58cf8d25ae93fcded
parentnet: thunder: fix a potential NULL pointer dereference (diff)
downloadlinux-dev-f2feaefdabb0a6253aa020f65e7388f07a9ed47c.tar.xz
linux-dev-f2feaefdabb0a6253aa020f65e7388f07a9ed47c.zip
tcp: Don't access TCP_SKB_CB before initializing it
Since commit eeea10b83a13 ("tcp: add tcp_v4_fill_cb()/tcp_v4_restore_cb()"), tcp_vX_fill_cb is only called after tcp_filter(). That means, TCP_SKB_CB(skb)->end_seq still points to the IP-part of the cb. We thus should not mock with it, as this can trigger bugs (thanks syzkaller): [ 12.349396] ================================================================== [ 12.350188] BUG: KASAN: slab-out-of-bounds in ip6_datagram_recv_specific_ctl+0x19b3/0x1a20 [ 12.351035] Read of size 1 at addr ffff88006adbc208 by task test_ip6_datagr/1799 Setting end_seq is actually no more necessary in tcp_filter as it gets initialized later on in tcp_vX_fill_cb. Cc: Eric Dumazet <edumazet@google.com> Fixes: eeea10b83a13 ("tcp: add tcp_v4_fill_cb()/tcp_v4_restore_cb()") Signed-off-by: Christoph Paasch <cpaasch@apple.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv4/tcp_ipv4.c9
1 files changed, 1 insertions, 8 deletions
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 831d844a27ca..277d71239d75 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1734,15 +1734,8 @@ EXPORT_SYMBOL(tcp_add_backlog);
int tcp_filter(struct sock *sk, struct sk_buff *skb)
{
struct tcphdr *th = (struct tcphdr *)skb->data;
- unsigned int eaten = skb->len;
- int err;
- err = sk_filter_trim_cap(sk, skb, th->doff * 4);
- if (!err) {
- eaten -= skb->len;
- TCP_SKB_CB(skb)->end_seq -= eaten;
- }
- return err;
+ return sk_filter_trim_cap(sk, skb, th->doff * 4);
}
EXPORT_SYMBOL(tcp_filter);