diff options
| author | Eric Dumazet <edumazet@google.com> | 2017-02-04 11:16:52 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-02-18 15:11:41 +0100 |
| commit | f5b54446630a973e1f27b68599366bbd0ac53066 (patch) | |
| tree | 7ce8d8407aae36524ebaaade2c60943485cf120b | |
| parent | d5b6fd77519df03feae24c1409eafb95f347ee88 (diff) | |
ipv4: keep skb->dst around in presence of IP options
[ Upstream commit 34b2cef20f19c87999fff3da4071e66937db9644 ]
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -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 f226f4086e05..65336f38a5d8 100644 --- a/net/ipv4/ip_sockglue.c +++ b/net/ipv4/ip_sockglue.c @@ -1215,7 +1215,14 @@ void ipv4_pktinfo_prepare(const struct sock *sk, 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, |