linux-kernel - [PATCH] net: handle the return value of pskb_carve_frag

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Date:   Sat, 15 Aug 2020 04:46:41 -0400
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <davem@...emloft.net>, <kuba@...nel.org>,
        <martin.varghese@...ia.com>, <fw@...len.de>, <pshelar@....org>,
        <dcaratti@...hat.com>, <edumazet@...gle.com>,
        <steffen.klassert@...unet.com>, <pabeni@...hat.com>,
        <shmulik@...anetworks.com>, <kyk.segfault@...il.com>,
        <sowmini.varadhan@...cle.com>
CC:     <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linmiaohe@...wei.com>
Subject: [PATCH] net: handle the return value of pskb_carve_frag_list() correctly

pskb_carve_frag_list() may return -ENOMEM in pskb_carve_inside_nonlinear().
we should handle this correctly or we would get wrong sk_buff.

Fixes: 6fa01ccd8830 ("skbuff: Add pskb_extract() helper function")
Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
---
 net/core/skbuff.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index bca0d3c7f114..afbc1a79dc8a 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -5987,9 +5987,13 @@ static int pskb_carve_inside_nonlinear(struct sk_buff *skb, const u32 off,
 	if (skb_has_frag_list(skb))
 		skb_clone_fraglist(skb);
 
-	if (k == 0) {
-		/* split line is in frag list */
-		pskb_carve_frag_list(skb, shinfo, off - pos, gfp_mask);
+	/* split line is in frag list */
+	if (k == 0 && pskb_carve_frag_list(skb, shinfo, off - pos, gfp_mask)) {
+		/* skb_frag_unref() is not needed here as shinfo->nr_frags = 0. */
+		if (skb_has_frag_list(skb))
+			kfree_skb_list(skb_shinfo(skb)->frag_list);
+		kfree(data);
+		return -ENOMEM;
 	}
 	skb_release_data(skb);
 
-- 
2.19.1