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Message-Id: <20191206033902.19638-1-xiyou.wangcong@gmail.com>
Date: Thu, 5 Dec 2019 19:39:02 -0800
From: Cong Wang <xiyou.wangcong@...il.com>
To: netdev@...r.kernel.org
Cc: Cong Wang <xiyou.wangcong@...il.com>,
Lorenzo Bianconi <lorenzo.bianconi@...hat.com>
Subject: [Patch net] gre: refetch erspan header from skb->data after pskb_may_pull()
After pskb_may_pull() we should always refetch the header
pointers from the skb->data in case it got reallocated.
In gre_parse_header(), the erspan header is still fetched
from the 'options' pointer which is fetched before
pskb_may_pull().
Found this during code review of a KMSAN bug report.
Fixes: cb73ee40b1b3 ("net: ip_gre: use erspan key field for tunnel lookup")
Cc: Lorenzo Bianconi <lorenzo.bianconi@...hat.com>
Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>
---
net/ipv4/gre_demux.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/ipv4/gre_demux.c b/net/ipv4/gre_demux.c
index 44bfeecac33e..5fd6e8ed02b5 100644
--- a/net/ipv4/gre_demux.c
+++ b/net/ipv4/gre_demux.c
@@ -127,7 +127,7 @@ int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,
if (!pskb_may_pull(skb, nhs + hdr_len + sizeof(*ershdr)))
return -EINVAL;
- ershdr = (struct erspan_base_hdr *)options;
+ ershdr = (struct erspan_base_hdr *)(skb->data + nhs + hdr_len);
tpi->key = cpu_to_be32(get_session_id(ershdr));
}
--
2.21.0
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