On Tue, Jun 11, 2019 at 10:51:23AM +0200, Daniel Vetter wrote: > On Tue, Jun 11, 2019 at 10:33:21AM +0200, Dmitry Vyukov wrote: > > On Tue, Jun 11, 2019 at 10:04 AM Daniel Vetter <daniel@xxxxxxxx> wrote: > > > > > > On Sat, Jun 08, 2019 at 04:22:06AM -0700, syzbot wrote: > > > > syzbot has found a reproducer for the following crash on: > > > > > > > > HEAD commit: 79c3ba32 Merge tag 'drm-fixes-2019-06-07-1' of git://anong.. > > > > git tree: upstream > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=1201b971a00000 > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=60564cb52ab29d5b > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=2ff1e7cb738fd3c41113 > > > > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14a3bf51a00000 > > > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=120d19f2a00000 > > > > > > Looking at the reproducer I don't see any calls to ioctl which could end > > > up anywhere in drm. > > > > > > > > The bug was bisected to: > > > > > > > > commit 0fff724a33917ac581b5825375d0b57affedee76 > > > > Author: Paul Kocialkowski <paul.kocialkowski@xxxxxxxxxxx> > > > > Date: Fri Jan 18 14:51:13 2019 +0000 > > > > > > > > drm/sun4i: backend: Use explicit fourcc helpers for packed YUV422 check > > > > > > And most definitely not in drm/sun4i. You can only hit this if you have > > > sun4i and run on arm, which per your config isn't the case. > > > > > > tldr; smells like bisect gone wrong. > > > -Daniel > > > > From the bisection log it looks like the bug is too hard to trigger > > for reliable bisection. So it probably classified one bad commit as > > good. But it should got quite close to the right one. > > Well statistically it'll get close, since there's a fair chance that it's > one of the later bisect results that got mischaracterized. > > But you can be equally unlucky, and if it's one of the earliers, then it > can easily be a few thousand commits of. Looking at the log it's mostly > bad, with a few good sprinkled in, which could just be reproduction > failures. So might very well be that the very first "good" result is > wrong. And that very first "good" decision cuts away a big pile of bpf > related commits. The next "good" decision then only cuts away a pile of > drm commits, but at that point you're already off the rails most likely. > > I'd say re-test on f90d64483ebd394958841f67f8794ab203b319a7 a few times, > I'm willing to bet that one is actually bad. btw if this theory is right, we have a 1-in-4 chance of a spurious "good" with your test. If you get 10 repeated "good" then that should be good enough to make playing the lottery a better endeavor :-) -Daniel > > Cheers, Daniel > > > > > > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1467550f200000 > > > > final crash: https://syzkaller.appspot.com/x/report.txt?x=1667550f200000 > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=1267550f200000 > > > > > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > > > Reported-by: syzbot+2ff1e7cb738fd3c41113@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > Fixes: 0fff724a3391 ("drm/sun4i: backend: Use explicit fourcc helpers for > > > > packed YUV422 check") > > > > > > > > WARNING: CPU: 0 PID: 8951 at kernel/bpf/core.c:851 bpf_jit_free+0x157/0x1b0 > > > > Kernel panic - not syncing: panic_on_warn set ... > > > > CPU: 0 PID: 8951 Comm: kworker/0:0 Not tainted 5.2.0-rc3+ #23 > > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > > > > Google 01/01/2011 > > > > Workqueue: events bpf_prog_free_deferred > > > > Call Trace: > > > > __dump_stack lib/dump_stack.c:77 [inline] > > > > dump_stack+0x172/0x1f0 lib/dump_stack.c:113 > > > > panic+0x2cb/0x744 kernel/panic.c:219 > > > > __warn.cold+0x20/0x4d kernel/panic.c:576 > > > > report_bug+0x263/0x2b0 lib/bug.c:186 > > > > fixup_bug arch/x86/kernel/traps.c:179 [inline] > > > > fixup_bug arch/x86/kernel/traps.c:174 [inline] > > > > do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:272 > > > > do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:291 > > > > invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:986 > > > > RIP: 0010:bpf_jit_free+0x157/0x1b0 > > > > Code: 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 5d 48 b8 00 02 00 00 > > > > 00 00 ad de 48 39 43 70 0f 84 05 ff ff ff e8 f9 b5 f4 ff <0f> 0b e9 f9 fe ff > > > > ff e8 bd 53 2d 00 e9 d9 fe ff ff 48 89 7d e0 e8 > > > > RSP: 0018:ffff88808886fcb0 EFLAGS: 00010293 > > > > RAX: ffff88808cb6c480 RBX: ffff88809051d280 RCX: ffffffff817ae68d > > > > RDX: 00000000> > > > > > > > -- > > > Daniel Vetter > > > Software Engineer, Intel Corporation > > > http://blog.ffwll.ch > > > > > > -- > > > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group. > > > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@xxxxxxxxxxxxxxxx. > > > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/20190611080431.GP21222%40phenom.ffwll.local. > > > For more options, visit https://groups.google.com/d/optout.00000000 RSI: ffffffff817bf0f7 RDI: ffff88809051d2f0 > > > > RBP: ffff88808886fcd0 R08: 1ffffffff14ccaa8 R09: fffffbfff14ccaa9 > > > > R10: fffffbfff14ccaa8 R11: ffffffff8a665547 R12: ffffc90001925000 > > > > R13: ffff88809051d2e8 R14: ffff8880a0e43900 R15: ffff8880ae834840 > > > > bpf_prog_free_deferred+0x27a/0x350 kernel/bpf/core.c:1984 > > > > process_one_work+0x989/0x1790 kernel/workqueue.c:2269 > > > > worker_thread+0x98/0xe40 kernel/workqueue.c:2415 > > > > kthread+0x354/0x420 kernel/kthread.c:255 > > > > ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 > > > > Kernel Offset: disabled > > > > Rebooting in 86400 seconds.. > > -- > Daniel Vetter > Software Engineer, Intel Corporation > http://blog.ffwll.ch -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
