On Mon, Aug 10, 2020 at 8:31 PM Marcelo Ricardo Leitner
[off-list ref] wrote:

On Mon, Aug 10, 2020 at 08:37:18AM -0700, syzbot wrote:

quoted

Hello,

syzbot found the following issue on:

HEAD commit:    fffe3ae0 Merge tag 'for-linus-hmm' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12f34d3a900000
kernel config:  https://syzkaller.appspot.com/x/.config?x=50463ec6729f9706
dashboard link: https://syzkaller.appspot.com/bug?extid=8f2165a7b1f2820feffc
compiler:       gcc (GCC) 10.1.0-syz 20200507
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1517701c900000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11b7e0e2900000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8f2165a7b1f2820feffc@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc000000004c: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000260-0x0000000000000267]
CPU: 0 PID: 12765 Comm: syz-executor391 Not tainted 5.8.0-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
RIP: 0010:sctp_ulpevent_notify_peer_addr_change+0xa9/0xad0 net/sctp/ulpevent.c:346

Crashed in code added by 45ebf73ebcec ("sctp: check assoc before
SCTP_ADDR_{MADE_PRIM, ADDED} event"), but it would have crashed a
couple of instructions later on already anyway.

I can't reproduce this crash, with the same commit and kernel config.
I'm not seeing how transport->asoc can be null at there.

I haven't been able to reproduce this yet either.

Doesn't this report have similarities with "general protection fault
in sctp_ulpevent_nofity_peer_addr_change" from 19 March 2020?
https://syzkaller.appspot.com/bug?extid=3950016bd95c2ca0377b