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Commit a2cf7bd7 authored by Kyle Zeng's avatar Kyle Zeng Committed by Greg Kroah-Hartman
Browse files

ipv4: fix null-deref in ipv4_link_failure 



[ Upstream commit 0113d9c9d1ccc07f5a3710dac4aa24b6d711278c ]

Currently, we assume the skb is associated with a device before calling
__ip_options_compile, which is not always the case if it is re-routed by
ipvs.
When skb->dev is NULL, dev_net(skb->dev) will become null-dereference.
This patch adds a check for the edge case and switch to use the net_device
from the rtable when skb->dev is NULL.

Fixes: ed0de45a1008 ("ipv4: recompile ip options in ipv4_link_failure")
Suggested-by: default avatarDavid Ahern <dsahern@kernel.org>
Signed-off-by: default avatarKyle Zeng <zengyhkyle@gmail.com>
Cc: Stephen Suryaputra <ssuryaextr@gmail.com>
Cc: Vadim Fedorenko <vfedorenko@novek.ru>
Reviewed-by: default avatarDavid Ahern <dsahern@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 83ff1953

net/ipv4/route.c

+3 −1
Original line number Diff line number Diff line
@@ -1215,6 +1215,7 @@ static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie) 


static void ipv4_send_dest_unreach(struct sk_buff *skb)

{

	struct net_device *dev;

	struct ip_options opt;

	int res;
@@ -1232,7 +1233,8 @@ static void ipv4_send_dest_unreach(struct sk_buff *skb) 
		opt.optlen = ip_hdr(skb)->ihl * 4 - sizeof(struct iphdr);



		rcu_read_lock();

		res = __ip_options_compile(dev_net(skb->dev), &opt, skb, NULL);

		dev = skb->dev ? skb->dev : skb_rtable(skb)->dst.dev;

		res = __ip_options_compile(dev_net(dev), &opt, skb, NULL);

		rcu_read_unlock();



		if (res)