In rose_send_frame(), when comparing two ax.25 addresses, it assigns rose_call to either global ROSE callsign or default port, but when the former block triggers and rose_call is assigned by (ax25_address *)neigh->dev->dev_addr, a NULL pointer is dereferenced by 'neigh' when dereferencing 'dev'.
- net/rose/rose_link.c This bug seems to get triggered in this line: rose_call = (ax25_address *)neigh->dev->dev_addr; Prevent it by checking NULL condition for neigh->dev before comparing addressed for rose_call initialization. Reported-by: syzbot+a1c743815982d9496...@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?id=9d2a7ca8c7f2e4b682c97578dfa3f236258300b3 Signed-off-by: Anmol Karn <anmol.karan...@gmail.com> --- I am bit sceptical about the error return code, please suggest if anything else is appropriate in place of '-ENODEV'. net/rose/rose_link.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/rose/rose_link.c b/net/rose/rose_link.c index f6102e6f5161..92ea6a31d575 100644 --- a/net/rose/rose_link.c +++ b/net/rose/rose_link.c @@ -97,6 +97,9 @@ static int rose_send_frame(struct sk_buff *skb, struct rose_neigh *neigh) ax25_address *rose_call; ax25_cb *ax25s; + if (!neigh->dev) + return -ENODEV; + if (ax25cmp(&rose_callsign, &null_ax25_address) == 0) rose_call = (ax25_address *)neigh->dev->dev_addr; else -- 2.28.0
