This is a note to let you know that I've just added the patch titled
ipv4: keep skb->dst around in presence of IP options
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ipv4-keep-skb-dst-around-in-presence-of-ip-options.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Tue Feb 14 16:29:59 PST 2017
From: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Sat, 4 Feb 2017 11:16:52 -0800
Subject: ipv4: keep skb->dst around in presence of IP options
From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ 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@xxxxxxxxxx>
Reported-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv4/ip_sockglue.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -1192,7 +1192,14 @@ void ipv4_pktinfo_prepare(const struct s
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,
Patches currently in stable-queue which might be from edumazet@xxxxxxxxxx are
queue-4.4/ipv6-pointer-math-error-in-ip6_tnl_parse_tlv_enc_lim.patch
queue-4.4/netlabel-out-of-bound-access-in-cipso_v4_validate.patch
queue-4.4/packet-round-up-linear-to-header-len.patch
queue-4.4/tun-read-vnet_hdr_sz-once.patch
queue-4.4/ipv6-fix-ip6_tnl_parse_tlv_enc_lim.patch
queue-4.4/l2tp-do-not-use-udp_ioctl.patch
queue-4.4/tcp-fix-0-divide-in-__tcp_select_window.patch
queue-4.4/can-fix-kernel-panic-at-security_sock_rcv_skb.patch
queue-4.4/net-introduce-device-min_header_len.patch
queue-4.4/macvtap-read-vnet_hdr_size-once.patch
queue-4.4/tcp-avoid-infinite-loop-in-tcp_splice_read.patch
queue-4.4/mlx4-invoke-softirqs-after-napi_reschedule.patch
queue-4.4/ipv6-tcp-add-a-missing-tcp_v6_restore_cb.patch
queue-4.4/ipv4-keep-skb-dst-around-in-presence-of-ip-options.patch
queue-4.4/net-use-a-work-queue-to-defer-net_disable_timestamp-work.patch
queue-4.4/ip6_gre-fix-ip6gre_err-invalid-reads.patch