ipv4: keep skb->dst around in presence of IP options
authorEric Dumazet <edumazet@google.com>
Sat, 4 Feb 2017 19:16:52 +0000 (11:16 -0800)
committerDavid S. Miller <davem@davemloft.net>
Sun, 5 Feb 2017 00:42:28 +0000 (19:42 -0500)
commit34b2cef20f19c87999fff3da4071e66937db9644
tree8511da9643a776f79e6ec8e99bf438444e19c49c
parent5fa8bbda38c668e56b0c6cdecced2eac2fe36dec
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")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/ipv4/ip_sockglue.c