diff mbox series

[net-next,1/6] can: skb: alloc_can{,fd}_skb(): set "cf" to NULL if skb allocation fails

Message ID 20210407080118.1916040-2-mkl@pengutronix.de
State New
Headers show
Series [net-next,1/6] can: skb: alloc_can{,fd}_skb(): set "cf" to NULL if skb allocation fails | expand

Commit Message

Marc Kleine-Budde April 7, 2021, 8:01 a.m. UTC 
The handling of CAN bus errors typically consist of allocating a CAN
error SKB using alloc_can_err_skb() followed by stats handling and
filling the error details in the newly allocated CAN error SKB. Even
if the allocation of the SKB fails the stats handling should not be
skipped.

The common pattern in CAN drivers is to allocate the skb and work on
the struct can_frame pointer "cf", if it has been assigned by
alloc_can_err_skb().

|	skb = alloc_can_err_skb(priv->ndev, &cf);
|
| 	/* RX errors */
| 	if (bdiag1 & (MCP251XFD_REG_BDIAG1_DCRCERR |
| 		      MCP251XFD_REG_BDIAG1_NCRCERR)) {
| 		netdev_dbg(priv->ndev, "CRC error\n");
|
| 		stats->rx_errors++;
| 		if (cf)
| 			cf->data[3] |= CAN_ERR_PROT_LOC_CRC_SEQ;
| 	}

In case of an OOM alloc_can_err_skb() returns NULL, but doesn't set
"cf" to NULL as well. For the above pattern to work the "cf" has to be
initialized to NULL, which is easily forgotten.

To solve this kind of problems, set "cf" to NULL if
alloc_can_err_skb() returns NULL.

Link: https://lore.kernel.org/r/20210402102245.1512583-1-mkl@pengutronix.de
Suggested-by: Vincent MAILHOL <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/net/can/dev/skb.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)


base-commit: 0b35e0deb5bee7d4882356d6663522c1562a8321
diff mbox series

Patch

diff --git a/drivers/net/can/dev/skb.c b/drivers/net/can/dev/skb.c
index 387c0bc0fb9c..61660248c69e 100644
--- a/drivers/net/can/dev/skb.c
+++ b/drivers/net/can/dev/skb.c
@@ -183,8 +183,11 @@  struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf)
 
 	skb = netdev_alloc_skb(dev, sizeof(struct can_skb_priv) +
 			       sizeof(struct can_frame));
-	if (unlikely(!skb))
+	if (unlikely(!skb)) {
+		*cf = NULL;
+
 		return NULL;
+	}
 
 	skb->protocol = htons(ETH_P_CAN);
 	skb->pkt_type = PACKET_BROADCAST;
@@ -211,8 +214,11 @@  struct sk_buff *alloc_canfd_skb(struct net_device *dev,
 
 	skb = netdev_alloc_skb(dev, sizeof(struct can_skb_priv) +
 			       sizeof(struct canfd_frame));
-	if (unlikely(!skb))
+	if (unlikely(!skb)) {
+		*cfd = NULL;
+
 		return NULL;
+	}
 
 	skb->protocol = htons(ETH_P_CANFD);
 	skb->pkt_type = PACKET_BROADCAST;