On Tue, 17 Sep 2019, Dmitry Vyukov wrote: > On Mon, Sep 16, 2019 at 6:40 PM Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > > > > On Mon, 16 Sep 2019, syzbot wrote: > > > > > Hello, > > > > > > syzbot found the following crash on: > > > > > > HEAD commit: f0df5c1b 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=11512cd1600000 > > > kernel config: https://syzkaller.appspot.com/x/.config?x=5c6633fa4ed00be5 > > > dashboard link: https://syzkaller.appspot.com/bug?extid=19cf612d23f66bc19f22 > > > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16f92c6e600000 > > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10b9b85e600000 > > > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > > Reported-by: syzbot+19cf612d23f66bc19f22@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > > > ====================================================== > > > WARNING: possible circular locking dependency detected > > > 5.3.0-rc7+ #0 Not tainted > > > ------------------------------------------------------ > > > syz-executor071/1724 is trying to acquire lock: > > > 00000000f749c934 (rio500_mutex){+.+.}, at: open_rio+0x16/0xe0 > > > drivers/usb/misc/rio500.c:65 > > > > > > but task is already holding lock: > > > 000000009c24ba51 (minor_rwsem){++++}, at: usb_open+0x23/0x270 > > > drivers/usb/core/file.c:39 > > > > > > which lock already depends on the new lock. > > > > > > > > > the existing dependency chain (in reverse order) is: > > > > > > -> #1 (minor_rwsem){++++}: > > > down_write+0x92/0x150 kernel/locking/rwsem.c:1500 > > > usb_register_dev drivers/usb/core/file.c:187 [inline] > > > usb_register_dev+0x131/0x670 drivers/usb/core/file.c:156 > > > probe_rio.cold+0x53/0x237 drivers/usb/misc/rio500.c:474 > > > usb_probe_interface+0x305/0x7a0 drivers/usb/core/driver.c:361 > > > really_probe+0x281/0x6d0 drivers/base/dd.c:548 > > > driver_probe_device+0x101/0x1b0 drivers/base/dd.c:721 > > > __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:828 > > > bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:454 > > > __device_attach+0x217/0x360 drivers/base/dd.c:894 > > > bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514 > > > device_add+0xae6/0x16f0 drivers/base/core.c:2165 > > > usb_set_configuration+0xdf6/0x1670 drivers/usb/core/message.c:2023 > > > generic_probe+0x9d/0xd5 drivers/usb/core/generic.c:210 > > > usb_probe_device+0x99/0x100 drivers/usb/core/driver.c:266 > > > really_probe+0x281/0x6d0 drivers/base/dd.c:548 > > > driver_probe_device+0x101/0x1b0 drivers/base/dd.c:721 > > > __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:828 > > > bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:454 > > > __device_attach+0x217/0x360 drivers/base/dd.c:894 > > > bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514 > > > device_add+0xae6/0x16f0 drivers/base/core.c:2165 > > > usb_new_device.cold+0x6a4/0xe79 drivers/usb/core/hub.c:2536 > > > hub_port_connect drivers/usb/core/hub.c:5098 [inline] > > > hub_port_connect_change drivers/usb/core/hub.c:5213 [inline] > > > port_event drivers/usb/core/hub.c:5359 [inline] > > > hub_event+0x1b5c/0x3640 drivers/usb/core/hub.c:5441 > > > process_one_work+0x92b/0x1530 kernel/workqueue.c:2269 > > > worker_thread+0x96/0xe20 kernel/workqueue.c:2415 > > > kthread+0x318/0x420 kernel/kthread.c:255 > > > ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 > > > > > > -> #0 (rio500_mutex){+.+.}: > > > check_prev_add kernel/locking/lockdep.c:2405 [inline] > > > check_prevs_add kernel/locking/lockdep.c:2507 [inline] > > > validate_chain kernel/locking/lockdep.c:2897 [inline] > > > __lock_acquire+0x1f7c/0x3b50 kernel/locking/lockdep.c:3880 > > > lock_acquire+0x127/0x320 kernel/locking/lockdep.c:4412 > > > __mutex_lock_common kernel/locking/mutex.c:930 [inline] > > > __mutex_lock+0x158/0x1360 kernel/locking/mutex.c:1077 > > > open_rio+0x16/0xe0 drivers/usb/misc/rio500.c:65 > > > usb_open+0x1df/0x270 drivers/usb/core/file.c:48 > > > chrdev_open+0x219/0x5c0 fs/char_dev.c:414 > > > do_dentry_open+0x494/0x1120 fs/open.c:797 > > > do_last fs/namei.c:3416 [inline] > > > path_openat+0x1430/0x3f50 fs/namei.c:3533 > > > do_filp_open+0x1a1/0x280 fs/namei.c:3563 > > > do_sys_open+0x3c0/0x580 fs/open.c:1089 > > > do_syscall_64+0xb7/0x580 arch/x86/entry/common.c:296 > > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > > > > > other info that might help us debug this: > > > > > > Possible unsafe locking scenario: > > > > > > CPU0 CPU1 > > > ---- ---- > > > lock(minor_rwsem); > > > lock(rio500_mutex); > > > lock(minor_rwsem); > > > lock(rio500_mutex); > > > > > > *** DEADLOCK *** > > > > > > 1 lock held by syz-executor071/1724: > > > #0: 000000009c24ba51 (minor_rwsem){++++}, at: usb_open+0x23/0x270 > > > drivers/usb/core/file.c:39 > > > > > > stack backtrace: > > > CPU: 0 PID: 1724 Comm: syz-executor071 Not tainted 5.3.0-rc7+ #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+0xca/0x13e lib/dump_stack.c:113 > > > check_noncircular+0x345/0x3e0 kernel/locking/lockdep.c:1741 > > > check_prev_add kernel/locking/lockdep.c:2405 [inline] > > > check_prevs_add kernel/locking/lockdep.c:2507 [inline] > > > validate_chain kernel/locking/lockdep.c:2897 [inline] > > > __lock_acquire+0x1f7c/0x3b50 kernel/locking/lockdep.c:3880 > > > lock_acquire+0x127/0x320 kernel/locking/lockdep.c:4412 > > > __mutex_lock_common kernel/locking/mutex.c:930 [inline] > > > __mutex_lock+0x158/0x1360 kernel/locking/mutex.c:1077 > > > open_rio+0x16/0xe0 drivers/usb/misc/rio500.c:65 > > > usb_open+0x1df/0x270 drivers/usb/core/file.c:48 > > > chrdev_open+0x219/0x5c0 fs/char_dev.c:414 > > > do_dentry_open+0x494/0x1120 fs/open.c:797 > > > do_last fs/namei.c:3416 [inline] > > > path_openat+0x1430/0x3f50 fs/namei.c:3533 > > > do_filp_open+0x1a1/0x280 fs/namei.c:3563 > > > do_sys_open+0x3c0/0x580 fs/open.c:1089 > > > do_syscall_64+0xb7/0x580 arch/x86/entry/common.c:296 > > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > > RIP: 0033:0x401130 > > > Code: 01 f0 ff ff 0f 83 00 0b 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f > > > 44 00 00 83 3d 5d 0c 2d 00 00 75 14 b8 02 00 00 00 0f 05 <48> 3d 01 f0 ff > > > ff 0f 83 d4 0a 00 00 c3 48 83 ec 08 e8 3a 00 00 00 > > > RSP: 002b:00007ffca0216788 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 > > > RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000401130 > > > RDX: 0000000000000000 RSI: 0000000000000002 RDI: 00007ffca02167a0 > > > RBP: 00000000006cb018 R08: 0000000000000000 R09: 000000000000000f > > > R10: 0000000000000064 R11: 0000000000000246 R12: 0000000000402090 > > > R13: 0000000000402120 R14: 0000000000000000 R15: 00 > > > > > > > > > --- > > > 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 > > > > This is undoubted the same as the previous bug report. It should be > > fixed by commit 9472aff16ca0 in Greg KH's usb-next branch, but the > > fix is not yet in Linus's tree. > > > > #syz dup: possible deadlock in open_rio > > Are you ready to bet money that this is undoubtedly the same as the > previous one? ;) Yes. Although perhaps it depends on your criteria for deciding whether two bug reports are caused by the same bug... > syzbot never reports the same bug until the previous is completely > fixed. I see the commit in Linus tree. Which commit do you see? The one that may have originally been reported as fixing the bug probably was not the right one. > We will get version (3) of this bug soon. On Tue, 17 Sep 2019, Andrey Konovalov wrote: > Yeah, this one is confusing. If we look at the dashboard [1] we see > that the fixing commit for the original bug is "Revert "USB: rio500: > simplify locking"", which is in the usb-testing tree (btw, I've > switched syzbot from usb-next to usb-testing, as it looked more > relevant). So syzbot saw the Reported-by tag on that commit, and > decided that the fix is applied, so if another bug with the same > manifestation happens, it must be a different bug and should be > reported. Syzbot has no way to know that commit 9472aff16ca0 (with the > same Reported-by tag as "Revert "USB: rio500: simplify locking") is > the proper fix for this issue. > > Since you've marked this bug as a dup of a fixed bug with the fix > applied to syzbot's tree, syzbot reported another one named "possible > deadlock in open_rio (3)". I'm going to manually mark that one as > fixed by commit 9472aff16ca0. > > https://syzkaller.appspot.com/bug?id=5b6785f7f0febf30e2133fa6e6dab81683ffa1b5 Yes, that's right; 9472aff16ca0 is the correct fix -- and it isn't in Linus's tree yet. I don't even want to think about the state of the driver after the "Revert "USB: rio500: simplify locking" commit... Alan Stern
