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| author | Anant Thazhemadam <anant.thazhemadam@gmail.com> | 2020-11-04 03:09:06 +0530 |
|---|---|---|
| committer | Marc Kleine-Budde <mkl@pengutronix.de> | 2020-11-15 18:24:33 +0100 |
| commit | 9aa9379d8f868e91719333a7f063ccccc0579acc (patch) | |
| tree | e472898355217bc53a9ad1846eb77131f090f4e0 /net/can | |
| parent | c8c958a58fc67f353289986850a0edf553435702 (diff) | |
| download | linux-9aa9379d8f868e91719333a7f063ccccc0579acc.tar.bz2 | |
can: af_can: prevent potential access of uninitialized member in canfd_rcv()
In canfd_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 > CANFD_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: d4689846881d ("can: af_can: canfd_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/20201103213906.24219-3-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 e8d4e3ef5322..5d124c155904 100644 --- a/net/can/af_can.c +++ b/net/can/af_can.c @@ -703,16 +703,25 @@ static int canfd_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 != CANFD_MTU || - cfd->len > CANFD_MAX_DLEN)) { - pr_warn_once("PF_CAN: dropped non conform CAN FD skbuf: dev type %d, len %d, datalen %d\n", + if (unlikely(dev->type != ARPHRD_CAN || skb->len != CANFD_MTU)) { + pr_warn_once("PF_CAN: dropped non conform CAN FD 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 > CANFD_MAX_DLEN)) { + pr_warn_once("PF_CAN: dropped non conform CAN FD 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; } /* af_can protocol functions */ |