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authorAnant Thazhemadam <anant.thazhemadam@gmail.com>2020-11-04 03:09:05 +0530
committerMarc Kleine-Budde <mkl@pengutronix.de>2020-11-15 18:17:04 +0100
commitc8c958a58fc67f353289986850a0edf553435702 (patch)
tree60091d3a07e522b81ed5dd62ce67ffcd0e291747 /net
parentceb736e1d45c253f5e86b185ca9b497cdd43063f (diff)
can: af_can: prevent potential access of uninitialized member in can_rcv()
In can_rcv(), cfd->len is uninitialized when skb->len = 0, and this uninitialized cfd->len is accessed nonetheless by pr_warn_once(). Fix this uninitialized variable access by checking cfd->len's validity condition (cfd->len > CAN_MAX_DLEN) separately after the skb->len's condition is checked, and appropriately modify the log messages that are generated as well. In case either of the required conditions fail, the skb is freed and NET_RX_DROP is returned, same as before. Fixes: 8cb68751c115 ("can: af_can: can_rcv(): replace WARN_ONCE by pr_warn_once") Reported-by: syzbot+9bcb0c9409066696d3aa@syzkaller.appspotmail.com Tested-by: Anant Thazhemadam <anant.thazhemadam@gmail.com> Signed-off-by: Anant Thazhemadam <anant.thazhemadam@gmail.com> Link: https://lore.kernel.org/r/20201103213906.24219-2-anant.thazhemadam@gmail.com Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Diffstat (limited to 'net')
-rw-r--r--net/can/af_can.c19
1 files changed, 14 insertions, 5 deletions
diff --git a/net/can/af_can.c b/net/can/af_can.c
index 6373ab9c5507..e8d4e3ef5322 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -677,16 +677,25 @@ static int can_rcv(struct sk_buff *skb, struct net_device *dev,
{
struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
- if (unlikely(dev->type != ARPHRD_CAN || skb->len != CAN_MTU ||
- cfd->len > CAN_MAX_DLEN)) {
- pr_warn_once("PF_CAN: dropped non conform CAN skbuf: dev type %d, len %d, datalen %d\n",
+ if (unlikely(dev->type != ARPHRD_CAN || skb->len != CAN_MTU)) {
+ pr_warn_once("PF_CAN: dropped non conform CAN skbuff: dev type %d, len %d\n",
+ dev->type, skb->len);
+ goto free_skb;
+ }
+
+ /* This check is made separately since cfd->len would be uninitialized if skb->len = 0. */
+ if (unlikely(cfd->len > CAN_MAX_DLEN)) {
+ pr_warn_once("PF_CAN: dropped non conform CAN skbuff: dev type %d, len %d, datalen %d\n",
dev->type, skb->len, cfd->len);
- kfree_skb(skb);
- return NET_RX_DROP;
+ goto free_skb;
}
can_receive(skb, dev);
return NET_RX_SUCCESS;
+
+free_skb:
+ kfree_skb(skb);
+ return NET_RX_DROP;
}
static int canfd_rcv(struct sk_buff *skb, struct net_device *dev,