Re: WARNING in zd_mac_clear

[Oliver Neukum <oneukum@suse.com>]

Am Mittwoch, den 07.08.2019, 16:07 +0200 schrieb Andrey Konovalov:
> On Fri, Apr 12, 2019 at 1:46 PM syzbot
> <syzbot+74c65761783d66a9c97c@syzkaller.appspotmail.com> wrote:
> > 
> > Hello,
> > 
> > syzbot found the following crash on:
> > 
> > HEAD commit:    9a33b369 usb-fuzzer: main usb gadget fuzzer driver
> > git tree:       https://github.com/google/kasan/tree/usb-fuzzer
> > console output: https://syzkaller.appspot.com/x/log.txt?x=101a06dd200000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=23e37f59d94ddd15
> > dashboard link: https://syzkaller.appspot.com/bug?extid=74c65761783d66a9c97c
> > compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1170c22d200000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1496adbb200000
> > 
> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > Reported-by: syzbot+74c65761783d66a9c97c@syzkaller.appspotmail.com
> > 
> > usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
> > usb 1-1: config 0 descriptor??
> > usb 1-1: reset low-speed USB device number 2 using dummy_hcd
> > usb 1-1: read over firmware interface failed: -71
> > usb 1-1: reset low-speed USB device number 2 using dummy_hcd
> > WARNING: CPU: 1 PID: 21 at drivers/net/wireless/zydas/zd1211rw/zd_mac.c:238
> > zd_mac_clear+0xb0/0xe0 drivers/net/wireless/zydas/zd1211rw/zd_mac.c:238
> > Kernel panic - not syncing: panic_on_warn set ...
> > CPU: 1 PID: 21 Comm: kworker/1:1 Not tainted 5.1.0-rc4-319354-g9a33b36 #3
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> > Google 01/01/2011
> > Workqueue: usb_hub_wq hub_event
> > Call Trace:
> >   __dump_stack lib/dump_stack.c:77 [inline]
> >   dump_stack+0xe8/0x16e lib/dump_stack.c:113
> >   panic+0x29d/0x5f2 kernel/panic.c:214
> >   __warn.cold+0x20/0x48 kernel/panic.c:571
> >   report_bug+0x262/0x2a0 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+0x130/0x1f0 arch/x86/kernel/traps.c:272
> >   do_invalid_op+0x37/0x40 arch/x86/kernel/traps.c:291
> >   invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:973
> > RIP: 0010:zd_mac_clear+0xb0/0xe0
> > drivers/net/wireless/zydas/zd1211rw/zd_mac.c:238
> > Code: e8 85 d0 60 f8 48 8d bb f8 2b 00 00 be ff ff ff ff e8 54 5a 46 f8 31
> > ff 89 c3 89 c6 e8 d9 d1 60 f8 85 db 75 d4 e8 60 d0 60 f8 <0f> 0b 5b 5d e9
> > 57 d0 60 f8 48 c7 c7 58 05 cb 93 e8 fb e0 97 f8 eb
> > RSP: 0018:ffff8880a85c7310 EFLAGS: 00010293
> > RAX: ffff8880a84de200 RBX: 0000000000000000 RCX: ffffffff8910f507
> > RDX: 0000000000000000 RSI: ffffffff8910f510 RDI: 0000000000000005
> > RBP: 0000000000000001 R08: ffff8880a84de200 R09: ffffed1012f83a0b
> > R10: ffffed1012f83a0a R11: ffff888097c1d057 R12: 00000000ffffffb9
> > R13: ffff888097c18b20 R14: ffff888099456630 R15: ffffffff8f979398
> >   probe+0x259/0x590 drivers/net/wireless/zydas/zd1211rw/zd_usb.c:1421
> >   usb_probe_interface+0x31d/0x820 drivers/usb/core/driver.c:361
> >   really_probe+0x2da/0xb10 drivers/base/dd.c:509
> >   driver_probe_device+0x21d/0x350 drivers/base/dd.c:671
> >   __device_attach_driver+0x1d8/0x290 drivers/base/dd.c:778
> >   bus_for_each_drv+0x163/0x1e0 drivers/base/bus.c:454
> >   __device_attach+0x223/0x3a0 drivers/base/dd.c:844
> >   bus_probe_device+0x1f1/0x2a0 drivers/base/bus.c:514
> >   device_add+0xad2/0x16e0 drivers/base/core.c:2106
> >   usb_set_configuration+0xdf7/0x1740 drivers/usb/core/message.c:2021
> >   generic_probe+0xa2/0xda drivers/usb/core/generic.c:210
> >   usb_probe_device+0xc0/0x150 drivers/usb/core/driver.c:266
> >   really_probe+0x2da/0xb10 drivers/base/dd.c:509
> >   driver_probe_device+0x21d/0x350 drivers/base/dd.c:671
> >   __device_attach_driver+0x1d8/0x290 drivers/base/dd.c:778
> >   bus_for_each_drv+0x163/0x1e0 drivers/base/bus.c:454
> >   __device_attach+0x223/0x3a0 drivers/base/dd.c:844
> >   bus_probe_device+0x1f1/0x2a0 drivers/base/bus.c:514
> >   device_add+0xad2/0x16e0 drivers/base/core.c:2106
> >   usb_new_device.cold+0x537/0xccf drivers/usb/core/hub.c:2534
> >   hub_port_connect drivers/usb/core/hub.c:5089 [inline]
> >   hub_port_connect_change drivers/usb/core/hub.c:5204 [inline]
> >   port_event drivers/usb/core/hub.c:5350 [inline]
> >   hub_event+0x138e/0x3b00 drivers/usb/core/hub.c:5432
> >   process_one_work+0x90f/0x1580 kernel/workqueue.c:2269
> >   worker_thread+0x9b/0xe20 kernel/workqueue.c:2415
> >   kthread+0x313/0x420 kernel/kthread.c:253
> >   ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
> > Kernel Offset: disabled
> > Rebooting in 86400 seconds..
> 
> This USB bug is the second most frequently triggered one with over 10k
> kernel crashes.

As far as I can tell this is a false positive. Didn't I submit this
upstream?

#syz test: https://github.com/google/kasan.git 9a33b369

From ae999d5a437850b65497df7dcca3ffc10f75e697 Mon Sep 17 00:00:00 2001
From: Oliver Neukum <oneukum@suse.com>
Date: Tue, 30 Jul 2019 15:59:03 +0200
Subject: [PATCH] zdnet: remove false assertion from zd_mac_clear()

The function is called before the lock which is asserted was ever used.
Just remove it.

Reported-by: syzbot+74c65761783d66a9c97c@syzkaller.appspotmail.com
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
 drivers/net/wireless/zydas/zd1211rw/zd_mac.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/net/wireless/zydas/zd1211rw/zd_mac.c b/drivers/net/wireless/zydas/zd1211rw/zd_mac.c
index da7e63fca9f5..a9999d10ae81 100644
--- a/drivers/net/wireless/zydas/zd1211rw/zd_mac.c
+++ b/drivers/net/wireless/zydas/zd1211rw/zd_mac.c
@@ -223,7 +223,6 @@ void zd_mac_clear(struct zd_mac *mac)
 {
 	flush_workqueue(zd_workqueue);
 	zd_chip_clear(&mac->chip);
-	lockdep_assert_held(&mac->lock);
 	ZD_MEMCLEAR(mac, sizeof(struct zd_mac));
 }
 
-- 
2.16.4