On Thu, Jun 7, 2018 at 2:41 PM, Ben Greear <gree...@candelatech.com> wrote: > On 06/07/2018 02:29 PM, Cong Wang wrote: >> >> On Thu, Jun 7, 2018 at 9:06 AM, <gree...@candelatech.com> wrote: >>> >>> --- a/include/net/fq_impl.h >>> +++ b/include/net/fq_impl.h >>> @@ -80,6 +80,9 @@ static struct sk_buff *fq_tin_dequeue(struct fq *fq, >>> >>> flow = list_first_entry(head, struct fq_flow, flowchain); >>> >>> + if (WARN_ON_ONCE(!flow)) >>> + return NULL; >>> + >> >> >> How could even possibly list_first_entry() returns NULL? >> You need list_first_entry_or_null(). >> > > I don't know for certain flow as null, but something was NULL in this method > near that line and it looked like a likely culprit. > > I guess possibly tin or fq was passed in as NULL?
A NULL pointer is not always 0. You can trigger a NULL-ptr-def with 0x3c too, but you are checking against 0 in your patch, that is the problem and that is why list_first_entry_or_null() exists.
