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From: Chengfeng Ye <cyeaa@connect.ust.hk>
To: krzysztof.kozlowski@canonical.com, davem@davemloft.net,
	kuba@kernel.org, wengjianfeng@yulong.com,
	dan.carpenter@oracle.com
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	Chengfeng Ye <cyeaa@connect.ust.hk>
Subject: [PATCH] nfc: pn533: Fix double free when pn533_fill_fragment_skbs() fails
Date: Fri,  5 Nov 2021 06:18:51 -0700	[thread overview]
Message-ID: <20211105131851.30256-1-cyeaa@connect.ust.hk> (raw)

skb is already freed by dev_kfree_skb in pn533_fill_fragment_skbs,
but follow error handler branch when pn533_fill_fragment_skbs()
fails, skb is freed again, results in double free issue. Fix this
by not free skb when pn533_fill_fragment_skbs() return value <= 0.

Signed-off-by: Chengfeng Ye <cyeaa@connect.ust.hk>
---
 drivers/nfc/pn533/pn533.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/nfc/pn533/pn533.c b/drivers/nfc/pn533/pn533.c
index 787bcbd290f7..226ae4357f7f 100644
--- a/drivers/nfc/pn533/pn533.c
+++ b/drivers/nfc/pn533/pn533.c
@@ -2285,8 +2285,10 @@ static int pn533_transceive(struct nfc_dev *nfc_dev,
 		/* jumbo frame ? */
 		if (skb->len > PN533_CMD_DATAEXCH_DATA_MAXLEN) {
 			rc = pn533_fill_fragment_skbs(dev, skb);
-			if (rc <= 0)
-				goto error;
+			if (rc <= 0) {
+				kfree(arg);
+				return rc;
+			}
 
 			skb = skb_dequeue(&dev->fragment_skb);
 			if (!skb) {
@@ -2353,8 +2355,11 @@ static int pn533_tm_send(struct nfc_dev *nfc_dev, struct sk_buff *skb)
 	/* let's split in multiple chunks if size's too big */
 	if (skb->len > PN533_CMD_DATAEXCH_DATA_MAXLEN) {
 		rc = pn533_fill_fragment_skbs(dev, skb);
-		if (rc <= 0)
-			goto error;
+		if (rc <= 0) {
+			if (rc < 0)
+				skb_queue_purge(&dev->fragment_skb);
+			return rc;
+		}
 
 		/* get the first skb */
 		skb = skb_dequeue(&dev->fragment_skb);
-- 
2.17.1


                 reply	other threads:[~2021-11-05 13:19 UTC|newest]

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