[PATCH net-next] net: asix: add proper error handling of usb read errors

Pavel Skripkin
2022-02-06T18:05:37Z

Syzbot once again hit uninit value in asix driver. The problem still the
same -- asix_read_cmd() reads less bytes, than was requested by caller.

Since all read requests are performed via asix_read_cmd() let's catch
usb related error there and add __must_check notation to be sure all
callers actually check return value.

So, this patch adds sanity check inside asix_read_cmd(), that simply
checks if bytes read are not less, than was requested and adds missing
error handling of asix_read_cmd() all across the driver code.

Fixes: d9fe64e51114 ("net: asix: Add in_pm parameter")
Reported-and-tested-by: syzbot+6ca9f7867b77c2d316ac@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Tested-by: Oleksij Rempel <o.rempel@pengutronix.de>
---

Changes since RFT:
- Added Tested-by: tag

---
drivers/net/usb/asix.h | 4 ++--
drivers/net/usb/asix_common.c | 19 +++++++++++++------
drivers/net/usb/asix_devices.c | 21 ++++++++++++++++++---
3 files changed, 33 insertions(+), 11 deletions(-)

diff --git a/drivers/net/usb/asix.h b/drivers/net/usb/asix.h
index 2a1e31def..4334aafab 100644
--- a/drivers/net/usb/asix.h
+++ b/drivers/net/usb/asix.h
@@ -192,8 +192,8 @@ extern const struct driver_info ax88172a_info;
/* ASIX specific flags */
#define FLAG_EEPROM_MAC (1UL << 0) /* init device MAC from eeprom */

-int asix_read_cmd(struct usbnet *dev, u8 cmd, u16 value, u16 index,
- u16 size, void *data, int in_pm);
+int __must_check asix_read_cmd(struct usbnet *dev, u8 cmd, u16 value, u16 index,
+ u16 size, void *data, int in_pm);

int asix_write_cmd(struct usbnet *dev, u8 cmd, u16 value, u16 index,
u16 size, void *data, int in_pm);
diff --git a/drivers/net/usb/asix_common.c b/drivers/net/usb/asix_common.c
index 71682970b..524805285 100644
--- a/drivers/net/usb/asix_common.c
+++ b/drivers/net/usb/asix_common.c
@@ -11,8 +11,8 @@

#define AX_HOST_EN_RETRIES 30

-int asix_read_cmd(struct usbnet *dev, u8 cmd, u16 value, u16 index,
- u16 size, void *data, int in_pm)
+int __must_check asix_read_cmd(struct usbnet *dev, u8 cmd, u16 value, u16 index,
+ u16 size, void *data, int in_pm)
{
int ret;
int (*fn)(struct usbnet *, u8, u8, u16, u16, void *, u16);
@@ -27,9 +27,12 @@ int asix_read_cmd(struct usbnet *dev, u8 cmd, u16 value, u16 index,
ret = fn(dev, cmd, USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
value, index, data, size);

- if (unlikely(ret < 0))
+ if (unlikely(ret < size)) {
+ ret = ret < 0 ? ret : -ENODATA;
+
netdev_warn(dev->net, "Failed to read reg index 0x%04x: %d\n",
index, ret);
+ }

return ret;
}
@@ -79,7 +82,7 @@ static int asix_check_host_enable(struct usbnet *dev, int in_pm)
0, 0, 1, &smsr, in_pm);
if (ret == -ENODEV)
break;
- else if (ret < sizeof(smsr))
+ else if (ret < 0)
continue;
else if (smsr & AX_HOST_EN)
break;
@@ -579,8 +582,12 @@ int asix_mdio_read_nopm(struct net_device *netdev, int phy_id, int loc)
return ret;
}

- asix_read_cmd(dev, AX_CMD_READ_MII_REG, phy_id,
- (__u16)loc, 2, &res, 1);
+ ret = asix_read_cmd(dev, AX_CMD_READ_MII_REG, phy_id,
+ (__u16)loc, 2, &res, 1);
+ if (ret < 0) {
+ mutex_unlock(&dev->phy_mutex);
+ return ret;
+ }
asix_set_hw_mii(dev, 1);
mutex_unlock(&dev->phy_mutex);

diff --git a/drivers/net/usb/asix_devices.c b/drivers/net/usb/asix_devices.c
index 9b72334aa..6ea44e537 100644
--- a/drivers/net/usb/asix_devices.c
+++ b/drivers/net/usb/asix_devices.c
@@ -755,7 +755,12 @@ static int ax88772_bind(struct usbnet *dev, struct usb_interface *intf)
priv->phy_addr = ret;
priv->embd_phy = ((priv->phy_addr & 0x1f) == 0x10);

- asix_read_cmd(dev, AX_CMD_STATMNGSTS_REG, 0, 0, 1, &chipcode, 0);
+ ret = asix_read_cmd(dev, AX_CMD_STATMNGSTS_REG, 0, 0, 1, &chipcode, 0);
+ if (ret < 0) {
+ netdev_dbg(dev->net, "Failed to read STATMNGSTS_REG: %d\n", ret);
+ return ret;
+ }
+
chipcode &= AX_CHIPCODE_MASK;

ret = (chipcode == AX_AX88772_CHIPCODE) ? ax88772_hw_reset(dev, 0) :
@@ -919,11 +924,21 @@ static int ax88178_reset(struct usbnet *dev)
int gpio0 = 0;
u32 phyid;

- asix_read_cmd(dev, AX_CMD_READ_GPIOS, 0, 0, 1, &status, 0);
+ ret = asix_read_cmd(dev, AX_CMD_READ_GPIOS, 0, 0, 1, &status, 0);
+ if (ret < 0) {
+ netdev_dbg(dev->net, "Failed to read GPIOS: %d\n", ret);
+ return ret;
+ }
+
netdev_dbg(dev->net, "GPIO Status: 0x%04x\n", status);

asix_write_cmd(dev, AX_CMD_WRITE_ENABLE, 0, 0, 0, NULL, 0);
- asix_read_cmd(dev, AX_CMD_READ_EEPROM, 0x0017, 0, 2, &eeprom, 0);
+ ret = asix_read_cmd(dev, AX_CMD_READ_EEPROM, 0x0017, 0, 2, &eeprom, 0);
+ if (ret < 0) {
+ netdev_dbg(dev->net, "Failed to read EEPROM: %d\n", ret);
+ return ret;
+ }
+
asix_write_cmd(dev, AX_CMD_WRITE_DISABLE, 0, 0, 0, NULL, 0);

netdev_dbg(dev->net, "EEPROM index 0x17 is 0x%04x\n", eeprom);
--
2.34.1