netdev - [PATCH net 1/1] net: fix fraglist segmentation reference count leak

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Date:   Mon, 30 Mar 2020 18:51:29 +0200
From:   Florian Westphal <fw@...len.de>
To:     <netdev@...r.kernel.org>
Cc:     Florian Westphal <fw@...len.de>,
        Steffen Klassert <steffen.klassert@...unet.com>,
        Xiumei Mu <xmu@...hat.com>, Xin Long <lucien.xin@...il.com>
Subject: [PATCH net 1/1] net: fix fraglist segmentation reference count leak

Xin Long says:
 On udp rx path udp_rcv_segment() may do segment where the frag skbs
 will get the header copied from the head skb in skb_segment_list()
 by calling __copy_skb_header(), which could overwrite the frag skbs'
 extensions by __skb_ext_copy() and cause a leak.

 This issue was found after loading esp_offload where a sec path ext
 is set in the skb.

Fix this by discarding head state of the fraglist skb before replacing
its contents.

Fixes: 3a1296a38d0cf62 ("net: Support GRO/GSO fraglist chaining.")
Cc: Steffen Klassert <steffen.klassert@...unet.com>
Reported-by: Xiumei Mu <xmu@...hat.com>
Tested-by: Xin Long <lucien.xin@...il.com>
Signed-off-by: Florian Westphal <fw@...len.de>
---
 net/core/skbuff.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index e1101a4f90a6..bea447f38dcc 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3668,6 +3668,7 @@ struct sk_buff *skb_segment_list(struct sk_buff *skb,
 
 		skb_push(nskb, -skb_network_offset(nskb) + offset);
 
+		skb_release_head_state(nskb);
 		 __copy_skb_header(nskb, skb);
 
 		skb_headers_offset_update(nskb, skb_headroom(nskb) - skb_headroom(skb));
-- 
2.24.1