Messages in this thread | | | From | Vlad Buslov <> | Subject | Re: KASAN: null-ptr-deref Read in tcf_idrinfo_destroy | Date | Tue, 16 Feb 2021 18:12:29 +0200 |
| |
On Tue 16 Feb 2021 at 01:22, Cong Wang <xiyou.wangcong@gmail.com> wrote: > On Wed, Feb 10, 2021 at 9:53 PM syzbot > <syzbot+151e3e714d34ae4ce7e8@syzkaller.appspotmail.com> wrote: >> >> syzbot has found a reproducer for the following issue on: >> >> HEAD commit: 291009f6 Merge tag 'pm-5.11-rc8' of git://git.kernel.org/p.. >> git tree: upstream >> console output: https://syzkaller.appspot.com/x/log.txt?x=14470d18d00000 >> kernel config: https://syzkaller.appspot.com/x/.config?x=a53fd47f16f22f8c >> dashboard link: https://syzkaller.appspot.com/bug?extid=151e3e714d34ae4ce7e8 >> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15f45814d00000 >> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15f4aff8d00000 >> >> IMPORTANT: if you fix the issue, please add the following tag to the commit: >> Reported-by: syzbot+151e3e714d34ae4ce7e8@syzkaller.appspotmail.com >> >> ================================================================== >> BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:71 [inline] >> BUG: KASAN: null-ptr-deref in atomic_read include/asm-generic/atomic-instrumented.h:27 [inline] >> BUG: KASAN: null-ptr-deref in __tcf_idr_release net/sched/act_api.c:178 [inline] >> BUG: KASAN: null-ptr-deref in tcf_idrinfo_destroy+0x129/0x1d0 net/sched/act_api.c:598 >> Read of size 4 at addr 0000000000000010 by task kworker/u4:5/204 >> >> CPU: 0 PID: 204 Comm: kworker/u4:5 Not tainted 5.11.0-rc7-syzkaller #0 >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 >> Workqueue: netns cleanup_net >> Call Trace: >> __dump_stack lib/dump_stack.c:79 [inline] >> dump_stack+0x107/0x163 lib/dump_stack.c:120 >> __kasan_report mm/kasan/report.c:400 [inline] >> kasan_report.cold+0x5f/0xd5 mm/kasan/report.c:413 >> check_memory_region_inline mm/kasan/generic.c:179 [inline] >> check_memory_region+0x13d/0x180 mm/kasan/generic.c:185 >> instrument_atomic_read include/linux/instrumented.h:71 [inline] >> atomic_read include/asm-generic/atomic-instrumented.h:27 [inline] >> __tcf_idr_release net/sched/act_api.c:178 [inline] >> tcf_idrinfo_destroy+0x129/0x1d0 net/sched/act_api.c:598 >> tc_action_net_exit include/net/act_api.h:151 [inline] >> police_exit_net+0x168/0x360 net/sched/act_police.c:390 > > This is really strange. It seems we still left some -EBUSY placeholders > in the idr, however, we actually call tcf_action_destroy() to clean up > everything including -EBUSY ones on error path. > > What do you think, Vlad? > > Thanks.
Hi Cong,
I couldn't reproduce the issue with syzbot repro.c, but it looks like we are missing tcf_idr_insert_many() in exts->police handling code inside tcf_exts_validate() which calls tcf_action_init_1(). After recent changes action is no longer inserted in idr by init_1 and requires manual call to tcf_idr_insert_many(). I'll send a fix.
Regards, Vlad
| |