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can: skb: alloc_can{,fd}_skb(): set "cf" to NULL if skb allocation fails 

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>
Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Marc Kleine-Budde 2021-04-02 12:05:39 +02:00
parent 0b35e0deb5
commit c812948744
1 changed files with 8 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
drivers/net/can/dev/skb.c
View File

@ -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;