On Thu, 24 Oct 2019, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit: 22be26f7 usb-fuzzer: main usb gadget fuzzer driver > git tree: https://github.com/google/kasan.git usb-fuzzer > console output: https://syzkaller.appspot.com/x/log.txt?x=11e2fda7600000 > kernel config: https://syzkaller.appspot.com/x/.config?x=5fe29bc39eff9627 > dashboard link: https://syzkaller.appspot.com/bug?extid=8ab8bf161038a8768553 > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14f664e4e00000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14674000e00000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+8ab8bf161038a8768553@xxxxxxxxxxxxxxxxxxxxxxxxx > > divide error: 0000 [#1] SMP KASAN > CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.4.0-rc3+ #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > RIP: 0010:transfer drivers/usb/gadget/udc/dummy_hcd.c:1426 [inline] > RIP: 0010:dummy_timer+0xad5/0x2fa2 drivers/usb/gadget/udc/dummy_hcd.c:1950 > Code: 0f 84 f5 fd ff ff e8 8a 55 ab fd 89 de 44 89 e7 e8 70 56 ab fd 41 39 > dc 0f 82 b0 08 00 00 e8 72 55 ab fd 44 89 e0 31 d2 31 ff <f7> f3 89 d6 89 > 94 24 c0 00 00 00 e8 cb 56 ab fd 8b 94 24 c0 00 00 > RSP: 0018:ffff8881db209b20 EFLAGS: 00010046 > RAX: 0000000000000040 RBX: 0000000000000000 RCX: ffffffff8392c330 > RDX: 0000000000000000 RSI: ffffffff8392c33e RDI: 0000000000000000 > RBP: 0000000000000000 R08: ffffffff86c2b200 R09: ffffed103b641353 > R10: ffffed103b641352 R11: 0000000000000003 R12: 0000000000000040 > R13: ffff8881d58c0000 R14: dffffc0000000000 R15: ffff8881d78d5a00 > FS: 0000000000000000(0000) GS:ffff8881db200000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007fb771a61000 CR3: 00000001d2295000 CR4: 00000000001406f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > <IRQ> > call_timer_fn+0x179/0x650 kernel/time/timer.c:1404 > expire_timers kernel/time/timer.c:1449 [inline] > __run_timers kernel/time/timer.c:1773 [inline] > __run_timers kernel/time/timer.c:1740 [inline] > run_timer_softirq+0x5e3/0x1490 kernel/time/timer.c:1786 > __do_softirq+0x221/0x912 kernel/softirq.c:292 > invoke_softirq kernel/softirq.c:373 [inline] > irq_exit+0x178/0x1a0 kernel/softirq.c:413 > exiting_irq arch/x86/include/asm/apic.h:536 [inline] > smp_apic_timer_interrupt+0x12f/0x500 arch/x86/kernel/apic/apic.c:1137 > apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830 > </IRQ> > RIP: 0010:default_idle+0x28/0x2e0 arch/x86/kernel/process.c:581 > Code: 90 90 41 56 41 55 65 44 8b 2d f4 00 92 7a 41 54 55 53 0f 1f 44 00 00 > e8 c6 b2 d3 fb e9 07 00 00 00 0f 00 2d ea a5 52 00 fb f4 <65> 44 8b 2d d0 > 00 92 7a 0f 1f 44 00 00 5b 5d 41 5c 41 5d 41 5e c3 > RSP: 0018:ffffffff86c07da8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 > RAX: 0000000000000007 RBX: ffffffff86c2b200 RCX: 0000000000000000 > RDX: 0000000000000000 RSI: 0000000000000006 RDI: ffffffff86c2ba4c > RBP: fffffbfff0d85640 R08: ffffffff86c2b200 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > cpuidle_idle_call kernel/sched/idle.c:154 [inline] > do_idle+0x3b6/0x500 kernel/sched/idle.c:263 > cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:355 > start_kernel+0x82a/0x864 init/main.c:784 > secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:241 > Modules linked in: > ---[ end trace 02e2d9c7c53d85a5 ]--- > RIP: 0010:transfer drivers/usb/gadget/udc/dummy_hcd.c:1426 [inline] > RIP: 0010:dummy_timer+0xad5/0x2fa2 drivers/usb/gadget/udc/dummy_hcd.c:1950 > Code: 0f 84 f5 fd ff ff e8 8a 55 ab fd 89 de 44 89 e7 e8 70 56 ab fd 41 39 > dc 0f 82 b0 08 00 00 e8 72 55 ab fd 44 89 e0 31 d2 31 ff <f7> f3 89 d6 89 > 94 24 c0 00 00 00 e8 cb 56 ab fd 8b 94 24 c0 00 00 > RSP: 0018:ffff8881db209b20 EFLAGS: 00010046 > RAX: 0000000000000040 RBX: 0000000000000000 RCX: ffffffff8392c330 > RDX: 0000000000000000 RSI: ffffffff8392c33e RDI: 0000000000000000 > RBP: 0000000000000000 R08: ffffffff86c2b200 R09: ffffed103b641353 > R10: ffffed103b641352 R11: 0000000000000003 R12: 0000000000000040 > R13: ffff8881d58c0000 R14: dffffc0000000000 R15: ffff8881d78d5a00 > FS: 0000000000000000(0000) GS:ffff8881db200000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007fb771a61000 CR3: 00000001d2295000 CR4: 00000000001406f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > > --- > This bug is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. > > syzbot will keep track of this bug report. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > syzbot can test patches for this bug, for details see: > https://goo.gl/tpsmEJ#testing-patches Is this really the sort of thing we need to catch? It isn't a bug in any existing kernel code, as far as I know. Maybe only gadgetfs and configfs need to worry about it. Alan Stern #syz test: https://github.com/google/kasan.git 22be26f7 drivers/usb/gadget/udc/dummy_hcd.c | 2 ++ 1 file changed, 2 insertions(+) Index: usb-devel/drivers/usb/gadget/udc/dummy_hcd.c =================================================================== --- usb-devel.orig/drivers/usb/gadget/udc/dummy_hcd.c +++ usb-devel/drivers/usb/gadget/udc/dummy_hcd.c @@ -522,6 +522,8 @@ static int dummy_enable(struct usb_ep *_ * For SS devices the wMaxPacketSize is limited by 1024. */ max = usb_endpoint_maxp(desc); + if (max == 0) + return -EINVAL; /* drivers must not request bad settings, since lower levels * (hardware or its drivers) may not check. some endpoints
