diff options
| author | Eric Dumazet <edumazet@google.com> | 2017-02-04 11:16:52 -0800 |
|---|---|---|
| committer | Sean McCreary <mccreary@mcwest.org> | 2017-07-17 05:11:36 +0000 |
| commit | 60469792e168c25c2c3da51a3bb7773f8ca029db (patch) | |
| tree | e85565bf8ed1592c58c45953075912e5b46cef25 | |
| parent | 383328af7afb960739522c523b54ed985169486a (diff) | |
ipv4: keep skb->dst around in presence of IP options
Andrey Konovalov got crashes in __ip_options_echo() when a NULL skb->dst
is accessed.
ipv4_pktinfo_prepare() should not drop the dst if (evil) IP options
are present.
We could refine the test to the presence of ts_needtime or srr,
but IP options are not often used, so let's be conservative.
Thanks to syzkaller team for finding this bug.
Fixes: d826eb14ecef ("ipv4: PKTINFO doesnt need dst reference")
Change-Id: I4684e44431021585a6b967feb1cba2ded8c5bddc
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/ipv4/ip_sockglue.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c index 2fd0fba7712..acef56b65ba 100644 --- a/net/ipv4/ip_sockglue.c +++ b/net/ipv4/ip_sockglue.c @@ -1030,7 +1030,14 @@ void ipv4_pktinfo_prepare(struct sk_buff *skb) pktinfo->ipi_ifindex = 0; pktinfo->ipi_spec_dst.s_addr = 0; } - skb_dst_drop(skb); + /* We need to keep the dst for __ip_options_echo() + * We could restrict the test to opt.ts_needtime || opt.srr, + * but the following is good enough as IP options are not often used. + */ + if (unlikely(IPCB(skb)->opt.optlen)) + skb_dst_force(skb); + else + skb_dst_drop(skb); } int ip_setsockopt(struct sock *sk, int level, |