Re: KASAN: use-after-free Read in tick_sched_handle (3)

On Mon, Nov 19, 2018 at 8:10 PM, Frederic Weisbecker
[off-list ref] wrote:

On Mon, Nov 19, 2018 at 01:39:02PM -0800, syzbot wrote:

quoted

Hello,

syzbot found the following crash on:

HEAD commit:    bae4e109837b mlxsw: spectrum: Expose discard counters via ..
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=11b5e77b400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d86f24333880b605
dashboard link: https://syzkaller.appspot.com/bug?extid=999bca54de2ee169c021
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14b7d093400000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1487a225400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+999bca54de2ee169c021@syzkaller.appspotmail.com

IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready
8021q: adding VLAN 0 to HW filter on device team0
==================================================================
kasan: CONFIG_KASAN_INLINE enabled
BUG: KASAN: use-after-free in tick_sched_handle+0x16c/0x180
kernel/time/tick-sched.c:164

So tick_sched_timer() -> tick_sched_handle() is passed regs returned by
get_irq_regs() that seem to be junk.

Those regs should come from smp_apic_timer_interrupt().

Thoughts?

Looking at the reproducer it looks like some memory corruption in
networking stack. +netdev