Hello Sir, On Fri, Nov 06, 2020 at 01:04:27PM -0800, Saeed Mahameed wrote: > 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 > >
Thank you for your review will rectify these and send another version. Thanks, Anmol
