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ipv4: fix null-deref in ipv4_link_failure

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[ 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: David Ahern <dsahern@kernel.org>
Signed-off-by: Kyle Zeng <zengyhkyle@gmail.com>
Cc: Stephen Suryaputra <ssuryaextr@gmail.com>
Cc: Vadim Fedorenko <vfedorenko@novek.ru>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Kyle Zeng 2023-09-14 22:12:57 -07:00 committed by Greg Kroah-Hartman
parent 8f228c326d
commit 810fd23d97
1 changed files with 3 additions and 1 deletions
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4
net/ipv4/route.c
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@ -1221,6 +1221,7 @@ 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;
@ -1238,7 +1239,8 @@ 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)