WARNING in dummy_free_request

WARNING in dummy_free_request

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    7f0cd6c7 usb: gadget: add raw-gadget interface
git tree:       https://github.com/google/kasan.git usb-fuzzer
console output: https://syzkaller.appspot.com/x/log.txt?x=17b58e5ee00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f10b12ae04e03319
dashboard link: https://syzkaller.appspot.com/bug?extid=55ae006e0a1feae5aeab
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+55ae006e0a1feae5aeab@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 1 PID: 19332 at drivers/usb/gadget/udc/dummy_hcd.c:679 dummy_free_request+0x6c/0x80 drivers/usb/gadget/udc/dummy_hcd.c:679
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 19332 Comm: syz-executor.5 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0xef/0x16e lib/dump_stack.c:118
 panic+0x2aa/0x6e1 kernel/panic.c:221
 __warn.cold+0x2f/0x30 kernel/panic.c:582
 report_bug+0x27b/0x2f0 lib/bug.c:195
 fixup_bug arch/x86/kernel/traps.c:174 [inline]
 fixup_bug arch/x86/kernel/traps.c:169 [inline]
 do_error_trap+0x12b/0x1e0 arch/x86/kernel/traps.c:267
 do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:286
 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
RIP: 0010:dummy_free_request+0x6c/0x80 drivers/usb/gadget/udc/dummy_hcd.c:679
Code: c5 75 22 e8 26 06 96 fd 48 89 ef e8 3e 54 be fd 5b 5d e9 17 06 96 fd e8 12 06 96 fd 0f 0b 5b 5d e9 09 06 96 fd e8 04 06 96 fd <0f> 0b eb d5 48 89 ef e8 08 ae be fd eb c2 66 0f 1f 44 00 00 41 56
RSP: 0018:ffff8881c9eafdd8 EFLAGS: 00010016
RAX: 0000000000040000 RBX: ffff8881d0d5aa10 RCX: ffffc900012a0000
RDX: 000000000000012f RSI: ffffffff83a95c1c RDI: ffff8881d4d501c8
RBP: ffff8881d0d5aa00 R08: ffff8881d0f9b100 R09: ffffed103b666a84
R10: ffffed103b666a83 R11: ffff8881db33541b R12: 0000000000000212
R13: ffff8881ca832008 R14: 0000000000000000 R15: ffff8881ca832180
 raw_ioctl_ep_disable drivers/usb/gadget/legacy/raw_gadget.c:814 [inline]
 raw_ioctl+0x1281/0x19e0 drivers/usb/gadget/legacy/raw_gadget.c:1031
 vfs_ioctl fs/ioctl.c:47 [inline]
 ksys_ioctl+0x11a/0x180 fs/ioctl.c:763
 __do_sys_ioctl fs/ioctl.c:772 [inline]
 __se_sys_ioctl fs/ioctl.c:770 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:770
 do_syscall_64+0xb6/0x5a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c537
Code: 48 83 c4 08 48 89 d8 5b 5d c3 66 0f 1f 84 00 00 00 00 00 48 89 e8 48 f7 d8 48 39 c3 0f 92 c0 eb 92 66 90 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 0d b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f5040518388 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 000000000045c537
RDX: 0000000000000000 RSI: 0000000040045506 RDI: 0000000000000006
RBP: 0000000000000006 R08: 0000000000405f0f R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000c80508
R13: 00000000000004e8 R14: 0000000000000002 R15: 0000000000000000
Shutting down cpus with NMI
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

Re: WARNING in dummy_free_request

[Alan Stern]

On Fri, 21 Feb 2020, syzbot wrote:

> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:    7f0cd6c7 usb: gadget: add raw-gadget interface
> git tree:       https://github.com/google/kasan.git usb-fuzzer
> console output: https://syzkaller.appspot.com/x/log.txt?x=17b58e5ee00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=f10b12ae04e03319
> dashboard link: https://syzkaller.appspot.com/bug?extid=55ae006e0a1feae5aeab
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> 
> Unfortunately, I don't have any reproducer for this crash yet.
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+55ae006e0a1feae5aeab@syzkaller.appspotmail.com
> 
> ------------[ cut here ]------------
> WARNING: CPU: 1 PID: 19332 at drivers/usb/gadget/udc/dummy_hcd.c:679 dummy_free_request+0x6c/0x80 drivers/usb/gadget/udc/dummy_hcd.c:679
> Kernel panic - not syncing: panic_on_warn set ...
> CPU: 1 PID: 19332 Comm: syz-executor.5 Not tainted 5.6.0-rc1-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:77 [inline]
>  dump_stack+0xef/0x16e lib/dump_stack.c:118
>  panic+0x2aa/0x6e1 kernel/panic.c:221
>  __warn.cold+0x2f/0x30 kernel/panic.c:582
>  report_bug+0x27b/0x2f0 lib/bug.c:195
>  fixup_bug arch/x86/kernel/traps.c:174 [inline]
>  fixup_bug arch/x86/kernel/traps.c:169 [inline]
>  do_error_trap+0x12b/0x1e0 arch/x86/kernel/traps.c:267
>  do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:286
>  invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
> RIP: 0010:dummy_free_request+0x6c/0x80 drivers/usb/gadget/udc/dummy_hcd.c:679
> Code: c5 75 22 e8 26 06 96 fd 48 89 ef e8 3e 54 be fd 5b 5d e9 17 06 96 fd e8 12 06 96 fd 0f 0b 5b 5d e9 09 06 96 fd e8 04 06 96 fd <0f> 0b eb d5 48 89 ef e8 08 ae be fd eb c2 66 0f 1f 44 00 00 41 56
> RSP: 0018:ffff8881c9eafdd8 EFLAGS: 00010016
> RAX: 0000000000040000 RBX: ffff8881d0d5aa10 RCX: ffffc900012a0000
> RDX: 000000000000012f RSI: ffffffff83a95c1c RDI: ffff8881d4d501c8
> RBP: ffff8881d0d5aa00 R08: ffff8881d0f9b100 R09: ffffed103b666a84
> R10: ffffed103b666a83 R11: ffff8881db33541b R12: 0000000000000212
> R13: ffff8881ca832008 R14: 0000000000000000 R15: ffff8881ca832180
>  raw_ioctl_ep_disable drivers/usb/gadget/legacy/raw_gadget.c:814 [inline]
>  raw_ioctl+0x1281/0x19e0 drivers/usb/gadget/legacy/raw_gadget.c:1031

Andrey:

This could be a bug in your raw_gadget driver.  This particular WARN is
triggered when a gadget driver tries to call usb_ep_free_request() for
a request that is still in flight.

Alan Stern

Re: WARNING in dummy_free_request

[Andrey Konovalov]

On Fri, Feb 21, 2020 at 5:41 PM Alan Stern <stern@rowland.harvard.edu> wrote:
>
> On Fri, 21 Feb 2020, syzbot wrote:
>
> > Hello,
> >
> > syzbot found the following crash on:
> >
> > HEAD commit:    7f0cd6c7 usb: gadget: add raw-gadget interface
> > git tree:       https://github.com/google/kasan.git usb-fuzzer
> > console output: https://syzkaller.appspot.com/x/log.txt?x=17b58e5ee00000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=f10b12ae04e03319
> > dashboard link: https://syzkaller.appspot.com/bug?extid=55ae006e0a1feae5aeab
> > compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> >
> > Unfortunately, I don't have any reproducer for this crash yet.
> >
> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > Reported-by: syzbot+55ae006e0a1feae5aeab@syzkaller.appspotmail.com
> >
> > ------------[ cut here ]------------
> > WARNING: CPU: 1 PID: 19332 at drivers/usb/gadget/udc/dummy_hcd.c:679 dummy_free_request+0x6c/0x80 drivers/usb/gadget/udc/dummy_hcd.c:679
> > Kernel panic - not syncing: panic_on_warn set ...
> > CPU: 1 PID: 19332 Comm: syz-executor.5 Not tainted 5.6.0-rc1-syzkaller #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> > Call Trace:
> >  __dump_stack lib/dump_stack.c:77 [inline]
> >  dump_stack+0xef/0x16e lib/dump_stack.c:118
> >  panic+0x2aa/0x6e1 kernel/panic.c:221
> >  __warn.cold+0x2f/0x30 kernel/panic.c:582
> >  report_bug+0x27b/0x2f0 lib/bug.c:195
> >  fixup_bug arch/x86/kernel/traps.c:174 [inline]
> >  fixup_bug arch/x86/kernel/traps.c:169 [inline]
> >  do_error_trap+0x12b/0x1e0 arch/x86/kernel/traps.c:267
> >  do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:286
> >  invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
> > RIP: 0010:dummy_free_request+0x6c/0x80 drivers/usb/gadget/udc/dummy_hcd.c:679
> > Code: c5 75 22 e8 26 06 96 fd 48 89 ef e8 3e 54 be fd 5b 5d e9 17 06 96 fd e8 12 06 96 fd 0f 0b 5b 5d e9 09 06 96 fd e8 04 06 96 fd <0f> 0b eb d5 48 89 ef e8 08 ae be fd eb c2 66 0f 1f 44 00 00 41 56
> > RSP: 0018:ffff8881c9eafdd8 EFLAGS: 00010016
> > RAX: 0000000000040000 RBX: ffff8881d0d5aa10 RCX: ffffc900012a0000
> > RDX: 000000000000012f RSI: ffffffff83a95c1c RDI: ffff8881d4d501c8
> > RBP: ffff8881d0d5aa00 R08: ffff8881d0f9b100 R09: ffffed103b666a84
> > R10: ffffed103b666a83 R11: ffff8881db33541b R12: 0000000000000212
> > R13: ffff8881ca832008 R14: 0000000000000000 R15: ffff8881ca832180
> >  raw_ioctl_ep_disable drivers/usb/gadget/legacy/raw_gadget.c:814 [inline]
> >  raw_ioctl+0x1281/0x19e0 drivers/usb/gadget/legacy/raw_gadget.c:1031
>
> Andrey:
>
> This could be a bug in your raw_gadget driver.  This particular WARN is
> triggered when a gadget driver tries to call usb_ep_free_request() for
> a request that is still in flight.

Hi Alan,

It might. It's not obvious what's wrong though. raw_ioctl_ep_disable()
calls usb_ep_disable()->dummy_disable() first, that supposedly does
list_del_init(&req->queue). And then it calls
usb_ep_free_request()->dummy_free_request(), which for some reason
still causes the warning. And a racy queueing of another request
should be prevented by the disabling flag.

I'll take a closer look on Monday.

Thanks!

Re: WARNING in dummy_free_request

[Andrey Konovalov]

On Fri, Feb 21, 2020 at 7:44 PM Andrey Konovalov <andreyknvl@google.com> wrote:
>
> On Fri, Feb 21, 2020 at 5:41 PM Alan Stern <stern@rowland.harvard.edu> wrote:
> >
> > On Fri, 21 Feb 2020, syzbot wrote:
> >
> > > Hello,
> > >
> > > syzbot found the following crash on:
> > >
> > > HEAD commit:    7f0cd6c7 usb: gadget: add raw-gadget interface
> > > git tree:       https://github.com/google/kasan.git usb-fuzzer
> > > console output: https://syzkaller.appspot.com/x/log.txt?x=17b58e5ee00000
> > > kernel config:  https://syzkaller.appspot.com/x/.config?x=f10b12ae04e03319
> > > dashboard link: https://syzkaller.appspot.com/bug?extid=55ae006e0a1feae5aeab
> > > compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> > >
> > > Unfortunately, I don't have any reproducer for this crash yet.
> > >
> > > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > > Reported-by: syzbot+55ae006e0a1feae5aeab@syzkaller.appspotmail.com
> > >
> > > ------------[ cut here ]------------
> > > WARNING: CPU: 1 PID: 19332 at drivers/usb/gadget/udc/dummy_hcd.c:679 dummy_free_request+0x6c/0x80 drivers/usb/gadget/udc/dummy_hcd.c:679
> > > Kernel panic - not syncing: panic_on_warn set ...
> > > CPU: 1 PID: 19332 Comm: syz-executor.5 Not tainted 5.6.0-rc1-syzkaller #0
> > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> > > Call Trace:
> > >  __dump_stack lib/dump_stack.c:77 [inline]
> > >  dump_stack+0xef/0x16e lib/dump_stack.c:118
> > >  panic+0x2aa/0x6e1 kernel/panic.c:221
> > >  __warn.cold+0x2f/0x30 kernel/panic.c:582
> > >  report_bug+0x27b/0x2f0 lib/bug.c:195
> > >  fixup_bug arch/x86/kernel/traps.c:174 [inline]
> > >  fixup_bug arch/x86/kernel/traps.c:169 [inline]
> > >  do_error_trap+0x12b/0x1e0 arch/x86/kernel/traps.c:267
> > >  do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:286
> > >  invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
> > > RIP: 0010:dummy_free_request+0x6c/0x80 drivers/usb/gadget/udc/dummy_hcd.c:679
> > > Code: c5 75 22 e8 26 06 96 fd 48 89 ef e8 3e 54 be fd 5b 5d e9 17 06 96 fd e8 12 06 96 fd 0f 0b 5b 5d e9 09 06 96 fd e8 04 06 96 fd <0f> 0b eb d5 48 89 ef e8 08 ae be fd eb c2 66 0f 1f 44 00 00 41 56
> > > RSP: 0018:ffff8881c9eafdd8 EFLAGS: 00010016
> > > RAX: 0000000000040000 RBX: ffff8881d0d5aa10 RCX: ffffc900012a0000
> > > RDX: 000000000000012f RSI: ffffffff83a95c1c RDI: ffff8881d4d501c8
> > > RBP: ffff8881d0d5aa00 R08: ffff8881d0f9b100 R09: ffffed103b666a84
> > > R10: ffffed103b666a83 R11: ffff8881db33541b R12: 0000000000000212
> > > R13: ffff8881ca832008 R14: 0000000000000000 R15: ffff8881ca832180
> > >  raw_ioctl_ep_disable drivers/usb/gadget/legacy/raw_gadget.c:814 [inline]
> > >  raw_ioctl+0x1281/0x19e0 drivers/usb/gadget/legacy/raw_gadget.c:1031
> >
> > Andrey:
> >
> > This could be a bug in your raw_gadget driver.  This particular WARN is
> > triggered when a gadget driver tries to call usb_ep_free_request() for
> > a request that is still in flight.
>
> Hi Alan,
>
> It might. It's not obvious what's wrong though. raw_ioctl_ep_disable()
> calls usb_ep_disable()->dummy_disable() first, that supposedly does
> list_del_init(&req->queue). And then it calls
> usb_ep_free_request()->dummy_free_request(), which for some reason
> still causes the warning. And a racy queueing of another request
> should be prevented by the disabling flag.
>
> I'll take a closer look on Monday.

OK, I see the issue, will post v6 with a fix soon.

Re: WARNING in dummy_free_request

[Andrey Konovalov]

On Mon, Feb 24, 2020 at 4:48 PM Andrey Konovalov <andreyknvl@google.com> wrote:
>
> On Fri, Feb 21, 2020 at 7:44 PM Andrey Konovalov <andreyknvl@google.com> wrote:
> >
> > On Fri, Feb 21, 2020 at 5:41 PM Alan Stern <stern@rowland.harvard.edu> wrote:
> > >
> > > On Fri, 21 Feb 2020, syzbot wrote:
> > >
> > > > Hello,
> > > >
> > > > syzbot found the following crash on:
> > > >
> > > > HEAD commit:    7f0cd6c7 usb: gadget: add raw-gadget interface
> > > > git tree:       https://github.com/google/kasan.git usb-fuzzer
> > > > console output: https://syzkaller.appspot.com/x/log.txt?x=17b58e5ee00000
> > > > kernel config:  https://syzkaller.appspot.com/x/.config?x=f10b12ae04e03319
> > > > dashboard link: https://syzkaller.appspot.com/bug?extid=55ae006e0a1feae5aeab
> > > > compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> > > >
> > > > Unfortunately, I don't have any reproducer for this crash yet.
> > > >
> > > > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > > > Reported-by: syzbot+55ae006e0a1feae5aeab@syzkaller.appspotmail.com
> > > >
> > > > ------------[ cut here ]------------
> > > > WARNING: CPU: 1 PID: 19332 at drivers/usb/gadget/udc/dummy_hcd.c:679 dummy_free_request+0x6c/0x80 drivers/usb/gadget/udc/dummy_hcd.c:679
> > > > Kernel panic - not syncing: panic_on_warn set ...
> > > > CPU: 1 PID: 19332 Comm: syz-executor.5 Not tainted 5.6.0-rc1-syzkaller #0
> > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> > > > Call Trace:
> > > >  __dump_stack lib/dump_stack.c:77 [inline]
> > > >  dump_stack+0xef/0x16e lib/dump_stack.c:118
> > > >  panic+0x2aa/0x6e1 kernel/panic.c:221
> > > >  __warn.cold+0x2f/0x30 kernel/panic.c:582
> > > >  report_bug+0x27b/0x2f0 lib/bug.c:195
> > > >  fixup_bug arch/x86/kernel/traps.c:174 [inline]
> > > >  fixup_bug arch/x86/kernel/traps.c:169 [inline]
> > > >  do_error_trap+0x12b/0x1e0 arch/x86/kernel/traps.c:267
> > > >  do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:286
> > > >  invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
> > > > RIP: 0010:dummy_free_request+0x6c/0x80 drivers/usb/gadget/udc/dummy_hcd.c:679
> > > > Code: c5 75 22 e8 26 06 96 fd 48 89 ef e8 3e 54 be fd 5b 5d e9 17 06 96 fd e8 12 06 96 fd 0f 0b 5b 5d e9 09 06 96 fd e8 04 06 96 fd <0f> 0b eb d5 48 89 ef e8 08 ae be fd eb c2 66 0f 1f 44 00 00 41 56
> > > > RSP: 0018:ffff8881c9eafdd8 EFLAGS: 00010016
> > > > RAX: 0000000000040000 RBX: ffff8881d0d5aa10 RCX: ffffc900012a0000
> > > > RDX: 000000000000012f RSI: ffffffff83a95c1c RDI: ffff8881d4d501c8
> > > > RBP: ffff8881d0d5aa00 R08: ffff8881d0f9b100 R09: ffffed103b666a84
> > > > R10: ffffed103b666a83 R11: ffff8881db33541b R12: 0000000000000212
> > > > R13: ffff8881ca832008 R14: 0000000000000000 R15: ffff8881ca832180
> > > >  raw_ioctl_ep_disable drivers/usb/gadget/legacy/raw_gadget.c:814 [inline]
> > > >  raw_ioctl+0x1281/0x19e0 drivers/usb/gadget/legacy/raw_gadget.c:1031
> > >
> > > Andrey:
> > >
> > > This could be a bug in your raw_gadget driver.  This particular WARN is
> > > triggered when a gadget driver tries to call usb_ep_free_request() for
> > > a request that is still in flight.
> >
> > Hi Alan,
> >
> > It might. It's not obvious what's wrong though. raw_ioctl_ep_disable()
> > calls usb_ep_disable()->dummy_disable() first, that supposedly does
> > list_del_init(&req->queue). And then it calls
> > usb_ep_free_request()->dummy_free_request(), which for some reason
> > still causes the warning. And a racy queueing of another request
> > should be prevented by the disabling flag.
> >
> > I'll take a closer look on Monday.
>
> OK, I see the issue, will post v6 with a fix soon.

#syz invalid