On Thu, 2020-11-05 at 21:26 +0530, Anmol Karn wrote:
> rose_send_frame() dereferences `neigh->dev` when called from
> rose_transmit_clear_request(), and the first occurance of the `neigh`
> is in rose_loopback_timer() as `rose_loopback_neigh`, and it is
> initialized
> in rose_add_loopback_neigh() as NULL. i.e when `rose_loopback_neigh`
> used in
> rose_loopback_timer() its `->dev` was still NULL and
> rose_loopback_timer()
> was calling rose_rx_call_request() without checking for NULL.
>
> - net/rose/rose_link.c
> This bug seems to get triggered in this line:
>
> rose_call = (ax25_address *)neigh->dev->dev_addr;
>
> Fix it by adding NULL checking for `rose_loopback_neigh->dev` in
> rose_loopback_timer().
>
> Reported-and-tested-by:
> syzbot+a1c743815982d9496...@syzkaller.appspotmail.com
> Link:
> https://syzkaller.appspot.com/bug?id=9d2a7ca8c7f2e4b682c97578dfa3f236258300b3
>
> Signed-off-by: Anmol Karn <anmol.karan...@gmail.com>
missing proper fixes tag.
> ---
> net/rose/rose_loopback.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/rose/rose_loopback.c b/net/rose/rose_loopback.c
> index 7b094275ea8b..cd7774cb1d07 100644
> --- a/net/rose/rose_loopback.c
> +++ b/net/rose/rose_loopback.c
> @@ -96,7 +96,7 @@ static void rose_loopback_timer(struct timer_list
> *unused)
> }
>
> if (frametype == ROSE_CALL_REQUEST) {
> - if ((dev = rose_dev_get(dest)) != NULL) {
> + if (rose_loopback_neigh->dev && (dev =
> rose_dev_get(dest)) != NULL) {
> if (rose_rx_call_request(skb, dev,
> rose_loopback_neigh, lci_o) == 0)
> kfree_skb(skb);
> } else {
check patch is not happy:
WARNING:TYPO_SPELLING: 'occurance' may be misspelled - perhaps
'occurrence'?
#7:
rose_transmit_clear_request(), and the first occurance of the `neigh`
ERROR:ASSIGN_IN_IF: do not use assignment in if condition
#36: FILE: net/rose/rose_loopback.c:99:
+ if (rose_loopback_neigh->dev && (dev =
rose_dev_get(dest)) != NULL) {
total: 1 errors, 1 warnings, 0 checks, 8 lines checked
