diff options
| author | Christoph Paasch <cpaasch@apple.com> | 2019-03-11 19:41:05 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2019-03-11 23:36:49 +0100 |
| commit | f2feaefdabb0a6253aa020f65e7388f07a9ed47c (patch) | |
| tree | d79b2b98513771ba6e4460a58cf8d25ae93fcded /net | |
| parent | net: thunder: fix a potential NULL pointer dereference (diff) | |
| download | linux-f2feaefdabb0a6253aa020f65e7388f07a9ed47c.tar.xz linux-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>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/tcp_ipv4.c | 9 |
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); |