On Fri, Feb 21, 2020 at 7:44 PM Andrey Konovalov <andreyknvl@xxxxxxxxxx> wrote: > > On Fri, Feb 21, 2020 at 5:41 PM Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > > > ------------[ 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.
