[PATCH 4.9 150/207] nfc: pn533: Fix double free when pn533_fill_fragment_skbs() fails

Greg Kroah-Hartman
2021-11-24T12:22:55Z

From: Chengfeng Ye <cyeaa@connect.ust.hk>

[ Upstream commit 9fec40f850658e00a14a7dd9e06f7fbc7e59cc4a ]

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 in error path of pn533_fill_fragment_skbs.

Fixes: 963a82e07d4e ("NFC: pn533: Split large Tx frames in chunks")
Fixes: 93ad42020c2d ("NFC: pn533: Target mode Tx fragmentation support")
Signed-off-by: Chengfeng Ye <cyeaa@connect.ust.hk>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/nfc/pn533/pn533.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/nfc/pn533/pn533.c b/drivers/nfc/pn533/pn533.c
index 6c495664d2cb7..806309ee41657 100644
--- a/drivers/nfc/pn533/pn533.c
+++ b/drivers/nfc/pn533/pn533.c
@@ -2075,7 +2075,7 @@ static int pn533_fill_fragment_skbs(struct pn533 *dev, struct sk_buff *skb)
frag = pn533_alloc_skb(dev, frag_size);
if (!frag) {
skb_queue_purge(&dev->fragment_skb);
- break;
+ return -ENOMEM;
}

if (!dev->tgt_mode) {
@@ -2145,7 +2145,7 @@ 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)
+ if (rc < 0)
goto error;

skb = skb_dequeue(&dev->fragment_skb);
@@ -2217,7 +2217,7 @@ 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)
+ if (rc < 0)
goto error;

/* get the first skb */
--
2.33.0