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| author |   Anant Thazhemadam <anant.thazhemadam@gmail.com> | 2020-11-04 03:09:05 +0530 |
|---|---|---|
| committer |   Marc Kleine-Budde <mkl@pengutronix.de> | 2020-11-15 18:17:04 +0100 |
| commit | c8c958a58fc67f353289986850a0edf553435702 (patch) | |
| tree | 60091d3a07e522b81ed5dd62ce67ffcd0e291747 /net/can | |
| parent | ipv6: Fix error path to cancel the meseage (diff) | |
| download | linux-dev-c8c958a58fc67f353289986850a0edf553435702.tar.xz linux-dev-c8c958a58fc67f353289986850a0edf553435702.zip | |
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/can')
| -rw-r--r-- | net/can/af_can.c | 19 |
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, |