[syzbot] KMSAN: uninit-value in asix_mdio_write_nopm

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 724946410067 x86: kmsan: enable KMSAN builds for x86
git tree: https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=151d8ea9700000
kernel config: https://syzkaller.appspot.com/x/.config?x=28718f555f258365
dashboard link: https://syzkaller.appspot.com/bug?extid=737f7d251877e50f3dce
compiler: clang version 14.0.0 (/usr/local/google/src/llvm-git-monorepo 2b554920f11c8b763cd9ed9003f4e19b919b8e1f), GNU ld (GNU Binutils for Debian) 2.35.2

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+737f7d...@syzkaller.appspotmail.com

usb 6-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 6-1: Product: syz
usb 6-1: Manufacturer: syz
usb 6-1: SerialNumber: syz
usb 6-1: config 0 descriptor??
asix 6-1:0.0 (unnamed net_device) (uninitialized): Failed to read reg index 0x0000: -71
=====================================================
BUG: KMSAN: uninit-value in asix_check_host_enable drivers/net/usb/asix_common.c:84 [inline]
BUG: KMSAN: uninit-value in asix_mdio_write_nopm+0x556/0x9d0 drivers/net/usb/asix_common.c:605
asix_check_host_enable drivers/net/usb/asix_common.c:84 [inline]
asix_mdio_write_nopm+0x556/0x9d0 drivers/net/usb/asix_common.c:605
ax88772a_hw_reset+0xa67/0x12e0 drivers/net/usb/asix_devices.c:524
ax88772_bind+0x750/0x1770 drivers/net/usb/asix_devices.c:762
usbnet_probe+0x1251/0x4160 drivers/net/usb/usbnet.c:1747
usb_probe_interface+0xf19/0x1600 drivers/usb/core/driver.c:396
really_probe+0x653/0x14b0 drivers/base/dd.c:596
__driver_probe_device+0x3e9/0x530 drivers/base/dd.c:752
driver_probe_device drivers/base/dd.c:782 [inline]
__device_attach_driver+0x79f/0x1120 drivers/base/dd.c:899
bus_for_each_drv+0x2d6/0x3f0 drivers/base/bus.c:427
__device_attach+0x593/0x8e0 drivers/base/dd.c:970
device_initial_probe+0x4a/0x60 drivers/base/dd.c:1017
bus_probe_device+0x17b/0x3e0 drivers/base/bus.c:487
device_add+0x1fff/0x26e0 drivers/base/core.c:3405
usb_set_configuration+0x37e9/0x3ed0 drivers/usb/core/message.c:2170
usb_generic_driver_probe+0x13c/0x300 drivers/usb/core/generic.c:238
usb_probe_device+0x309/0x570 drivers/usb/core/driver.c:293
really_probe+0x653/0x14b0 drivers/base/dd.c:596
__driver_probe_device+0x3e9/0x530 drivers/base/dd.c:752
driver_probe_device drivers/base/dd.c:782 [inline]
__device_attach_driver+0x79f/0x1120 drivers/base/dd.c:899
bus_for_each_drv+0x2d6/0x3f0 drivers/base/bus.c:427
__device_attach+0x593/0x8e0 drivers/base/dd.c:970
device_initial_probe+0x4a/0x60 drivers/base/dd.c:1017
bus_probe_device+0x17b/0x3e0 drivers/base/bus.c:487
device_add+0x1fff/0x26e0 drivers/base/core.c:3405
usb_new_device+0x1b8e/0x2950 drivers/usb/core/hub.c:2566
hub_port_connect drivers/usb/core/hub.c:5358 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5502 [inline]
port_event drivers/usb/core/hub.c:5660 [inline]
hub_event+0x58e3/0x89e0 drivers/usb/core/hub.c:5742
process_one_work+0xdb6/0x1820 kernel/workqueue.c:2307
worker_thread+0x10b3/0x21e0 kernel/workqueue.c:2454
kthread+0x3c7/0x500 kernel/kthread.c:377
ret_from_fork+0x1f/0x30

Local variable smsr.i created at:
asix_mdio_write_nopm+0xe7/0x9d0 drivers/net/usb/asix_common.c:605
ax88772a_hw_reset+0xa67/0x12e0 drivers/net/usb/asix_devices.c:524

CPU: 1 PID: 3515 Comm: kworker/1:3 Not tainted 5.17.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: usb_hub_wq hub_event
=====================================================


---
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[Kosuke Fujimoto]

#syz test: https://github.com/google/kmsan.git master 

diff --git a/drivers/net/usb/asix_common.c b/drivers/net/usb/asix_common.c
index 71682970be58..1ec3e3acb2b3 100644
--- a/drivers/net/usb/asix_common.c
+++ b/drivers/net/usb/asix_common.c
@@ -68,7 +68,7 @@ void asix_write_cmd_async(struct usbnet *dev, u8 cmd, u16 value, u16 index,
 static int asix_check_host_enable(struct usbnet *dev, int in_pm)
 {
        int i, ret;
-       u8 smsr;
+       u8 smsr = 0;
 
        for (i = 0; i < AX_HOST_EN_RETRIES; ++i) {
                ret = asix_set_sw_mii(dev, in_pm);

Best regards,

Kosuke Fujimoto

[syzbot]

I see the command but can't find the corresponding bug.
Please resend the email to syzbo...@syzkaller.appspotmail.com address
that is the sender of the bug report (also present in the Reported-by tag).

>
> diff --git a/drivers/net/usb/asix_common.c b/drivers/net/usb/asix_common.c
> index 71682970be58..1ec3e3acb2b3 100644
> --- a/drivers/net/usb/asix_common.c
> +++ b/drivers/net/usb/asix_common.c
> @@ -68,7 +68,7 @@ void asix_write_cmd_async(struct usbnet *dev, u8 cmd, u16
> value, u16 index,
> static int asix_check_host_enable(struct usbnet *dev, int in_pm)
> {
> int i, ret;
> - u8 smsr;
> + u8 smsr = 0;
>
> for (i = 0; i < AX_HOST_EN_RETRIES; ++i) {
> ret = asix_set_sw_mii(dev, in_pm);
>
> Best regards,
> Kosuke Fujimoto
>

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[Pavel Skripkin]

+CC initial bug

Hi Kosuke,

On 3/25/22 20:21, Kosuke Fujimoto wrote:
> #syz test: https://github.com/google/kmsan.git master
>
> diff --git a/drivers/net/usb/asix_common.c b/drivers/net/usb/asix_common.c
> index 71682970be58..1ec3e3acb2b3 100644
> --- a/drivers/net/usb/asix_common.c
> +++ b/drivers/net/usb/asix_common.c
> @@ -68,7 +68,7 @@ void asix_write_cmd_async(struct usbnet *dev, u8 cmd, u16
> value, u16 index,
> static int asix_check_host_enable(struct usbnet *dev, int in_pm)
> {
> int i, ret;
> - u8 smsr;
> + u8 smsr = 0;
>
> for (i = 0; i < AX_HOST_EN_RETRIES; ++i) {
> ret = asix_set_sw_mii(dev, in_pm);
>

This bug does not have a reproducer, but most likely it's already fixed
in -next. This patch in -next strictly disables partial read via usb, so
all kind of usb read errors are addressed in this driver


#syz fix: net: asix: add proper error handling of usb read errors




With regards,
Pavel Skripkin

[David Kahurani]

It also does not look like there is a reproducer for this bug meaning it cannot be tested :-(

To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/0000000000004ae9dd05db0e3194%40google.com.Th