On Fri, Apr 28, 2017 at 6:08 AM, Andrey Konovalov <andreyk...@google.com> wrote: > Hi, > > I've got the following error report while fuzzing the kernel with syzkaller. > > On commit 5a7ad1146caa895ad718a534399e38bd2ba721b7 (4.11-rc8). > > C reproducer and .config are attached. > It takes 1-2 minutes of running the reproducer to trigger the issue. > > ------------[ cut here ]------------ > WARNING: CPU: 0 PID: 21 at net/ipv6/addrconf.c:894 > inet6_ifa_finish_destroy+0x12e/0x190 > Modules linked in: > CPU: 0 PID: 21 Comm: kworker/0:1 Not tainted 4.11.0-rc8+ #296 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 > Workqueue: ipv6_addrconf addrconf_dad_work > Call Trace: > __dump_stack lib/dump_stack.c:16 > dump_stack+0x292/0x398 lib/dump_stack.c:52 > __warn+0x19f/0x1e0 kernel/panic.c:549 > warn_slowpath_null+0x2c/0x40 kernel/panic.c:584 > inet6_ifa_finish_destroy+0x12e/0x190 c:894 > in6_ifa_put ./include/net/addrconf.h:330 > addrconf_dad_work+0x4e9/0x1040 net/ipv6/addrconf.c:3963
I don't look too much, but a quick glance shows in the following path: } else if (action == DAD_ABORT) { in6_ifa_hold(ifp); addrconf_dad_stop(ifp, 1); if (disable_ipv6) addrconf_ifdown(idev->dev, 0); goto out; } the inet6_addr could be removed from hash table in addrconf_ifdown() before calling in6_ifa_put(). which causes this warning.