WARNING in hwahc_probe

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: e17994d1 usb: core: kcov: collect coverage from usb comple..
git tree: https://github.com/google/kasan.git usb-fuzzer
console output: https://syzkaller.appspot.com/x/log.txt?x=12d170ade00000
kernel config: https://syzkaller.appspot.com/x/.config?x=5d64370c438bc60
dashboard link: https://syzkaller.appspot.com/bug?extid=df767d588771697b0433
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14ac8b91e00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1010e223e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+df767d...@syzkaller.appspotmail.com

pl2303 1-1:31.37: required endpoints missing
hwa-hc 1-1:31.37: Wire Adapter v219.213 newer than groked v1.0
hwa-hc 1-1:31.37: FIXME: USB_MAXCHILDREN too low for WUSB adapter (62 ports)
------------[ cut here ]------------
WARNING: CPU: 0 PID: 95 at lib/vsprintf.c:2512 vsnprintf+0xf46/0x14f0 lib/vsprintf.c:2512
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 95 Comm: kworker/0:2 Not tainted 5.6.0-rc5-syzkaller #0
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+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:vsnprintf+0xf46/0x14f0 lib/vsprintf.c:2512
Code: 10 83 c5 08 41 89 2f e8 f8 34 b3 fb 4c 89 f0 48 c1 e8 03 80 3c 18 00 0f 85 38 04 00 00 4d 8b 36 e9 bb f2 ff ff e8 da 34 b3 fb <0f> 0b 45 31 ed e9 71 f3 ff ff e8 cb 34 b3 fb 4c 89 e8 4c 89 ea 48
RSP: 0018:ffff8881d58c6fc8 EFLAGS: 00010293
RAX: ffff8881d7976200 RBX: fffffffffffffff7 RCX: ffffffff858c1258
RDX: 0000000000000000 RSI: ffffffff858c2106 RDI: 0000000000000007
RBP: ffffffff86881480 R08: ffff8881d7976200 R09: ffffed103ab18e4e
R10: ffffed103ab18e4d R11: ffff8881d58c7269 R12: ffff8881d58c7279
R13: fffffffffffffff7 R14: ffffffff86881480 R15: ffff8881d58c70c8
snprintf+0xbb/0xf0 lib/vsprintf.c:2707
hwahc_security_create drivers/staging/wusbcore/host/hwa-hc.c:683 [inline]
hwahc_create drivers/staging/wusbcore/host/hwa-hc.c:738 [inline]
hwahc_probe+0xfd6/0x1490 drivers/staging/wusbcore/host/hwa-hc.c:805
usb_probe_interface+0x310/0x800 drivers/usb/core/driver.c:374
really_probe+0x290/0xac0 drivers/base/dd.c:551
driver_probe_device+0x223/0x350 drivers/base/dd.c:724
__device_attach_driver+0x1d1/0x290 drivers/base/dd.c:831
bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:431
__device_attach+0x217/0x390 drivers/base/dd.c:897
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:491
device_add+0x1459/0x1bf0 drivers/base/core.c:2500
usb_set_configuration+0xe47/0x17d0 drivers/usb/core/message.c:2023
usb_generic_driver_probe+0x9d/0xe0 drivers/usb/core/generic.c:241
usb_probe_device+0xd9/0x230 drivers/usb/core/driver.c:272
really_probe+0x290/0xac0 drivers/base/dd.c:551
driver_probe_device+0x223/0x350 drivers/base/dd.c:724
__device_attach_driver+0x1d1/0x290 drivers/base/dd.c:831
bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:431
__device_attach+0x217/0x390 drivers/base/dd.c:897
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:491
device_add+0x1459/0x1bf0 drivers/base/core.c:2500
usb_new_device.cold+0x540/0xcd0 drivers/usb/core/hub.c:2548
hub_port_connect drivers/usb/core/hub.c:5195 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5335 [inline]
port_event drivers/usb/core/hub.c:5481 [inline]
hub_event+0x21cb/0x4300 drivers/usb/core/hub.c:5563
process_one_work+0x94b/0x1620 kernel/workqueue.c:2264
worker_thread+0x96/0xe20 kernel/workqueue.c:2410
kthread+0x318/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Kernel Offset: disabled
Rebooting in 86400 seconds..


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[Qiujun Huang]

The return value of snprintf is longer than expected if the string is
truncated. Bytes need to be checked here.

diff --git a/drivers/staging/wusbcore/host/hwa-hc.c
b/drivers/staging/wusbcore/host/hwa-hc.c
index 8d959e9..1475a48 100644
--- a/drivers/staging/wusbcore/host/hwa-hc.c
+++ b/drivers/staging/wusbcore/host/hwa-hc.c
@@ -680,10 +680,12 @@ static int hwahc_security_create(struct hwahc *hwahc)
break;
}
itr += etd->bLength;
- bytes += snprintf(buf + bytes, sizeof(buf) - bytes,
- "%s (0x%02x) ",
- wusb_et_name(etd->bEncryptionType),
- etd->bEncryptionValue);
+
+ if (sizeof(buf) > bytes)
+ bytes += snprintf(buf + bytes, sizeof(buf) - bytes,
+ "%s (0x%02x) ",
+ wusb_et_name(etd->bEncryptionType),
+ etd->bEncryptionValue);
wusbhc->ccm1_etd = etd;
}
dev_info(dev, "supported encryption types: %s\n", buf);

[Greg KH]

On Sun, Mar 22, 2020 at 03:53:44PM +0800, Qiujun Huang wrote:
> The return value of snprintf is longer than expected if the string is
> truncated. Bytes need to be checked here.
>
> diff --git a/drivers/staging/wusbcore/host/hwa-hc.c
> b/drivers/staging/wusbcore/host/hwa-hc.c
> index 8d959e9..1475a48 100644
> --- a/drivers/staging/wusbcore/host/hwa-hc.c
> +++ b/drivers/staging/wusbcore/host/hwa-hc.c

This file is no longer in the linux-next tree and will be deleted in the
next kernel release.

Also, no one has this hardware so there's no real security issue here at
all.

And finally, you forgot a signed-off-by line on your patch :(

thanks,

greg k-h

[Qiujun Huang]

Get that, thanks.

>
> thanks,
>
> greg k-h

[Eric Biggers]

Invalidating this bug because drivers/staging/wusbcore/ has been deleted.

#syz invalid