Hi, rtl8712 developers and stanging maintainers!
In this patch series I rewrote error handling approach in rtl8712 driver.
Detailed description can be found in commit messages. In short:
There was strage approach to handle fw load error. For some reason fw callback
was doing clean up stuff which can lead to UAF bug. For example:
CPU0 CPU1
r871xu_dev_remove()
rtl871x_load_fw_cb()
free_netdev(netdev)
wait_for_completion(netdev_priv->compl) <- UAF, slab-out-of-bound or smth else
I've added free_netdev() call in my previous patch to this driver:
e02a3b945816 ("staging: rtl8712: fix memory leak in rtl871x_load_fw_cb") to avoid
memory leak and I believed, that this approach won't trigger anything else, but,
unfortunately, I was wrong. Syzbot found 2 bugs [1] [2] and I decided to complely
rewrite error handling in case of fw load failure. This patch series was tested
with both reproducers and did't trigger any bugs.
[1] https://syzkaller.appspot.com/bug?id=7646834b55c71c45ed85f601032daa6c23db0513
[2] https://syzkaller.appspot.com/bug?id=89c3ddb9936d3552995130298f1d2633ab9d3541
With regards,
Pavel Skripkin
Pavel Skripkin (2):
staging: rtl8712: get rid of flush_scheduled_work
staging: rtl8712: error handling refactoring
drivers/staging/rtl8712/hal_init.c | 30 ++++++++-----
drivers/staging/rtl8712/rtl8712_led.c | 8 ++++
drivers/staging/rtl8712/rtl871x_led.h | 1 +
drivers/staging/rtl8712/rtl871x_pwrctrl.c | 8 ++++
drivers/staging/rtl8712/rtl871x_pwrctrl.h | 1 +
drivers/staging/rtl8712/usb_intf.c | 51 ++++++++++-------------
6 files changed, 61 insertions(+), 38 deletions(-)
--
2.32.0
There was strange error handling logic in case of fw load failure. For
some reason fw loader callback was doing clean up stuff when fw is not
available. I don't see any reason behind doing this. Since this driver
doesn't have EEPROM firmware let's just disconnect it in case of fw load
failure. Doing clean up stuff in 2 different place which can run
concurently is not good idea and syzbot found 2 bugs related to this
strange approach.
So, in this pacth I deleted all clean up code from fw callback and made
a call to device_release_driver() under device_lock(parent) in case of fw
load failure. This approach is more generic and it defend driver from UAF
bugs, since all clean up code is moved to one place.
Fixes: e02a3b945816 ("staging: rtl8712: fix memory leak in rtl871x_load_fw_cb")
Fixes: 8c213fa59199 ("staging: r8712u: Use asynchronous firmware loading")
Reported-and-tested-by: [email protected]
Reported-and-tested-by: [email protected]
Signed-off-by: Pavel Skripkin <[email protected]>
---
drivers/staging/rtl8712/hal_init.c | 30 +++++++++++------
drivers/staging/rtl8712/usb_intf.c | 52 +++++++++++++-----------------
2 files changed, 43 insertions(+), 39 deletions(-)
diff --git a/drivers/staging/rtl8712/hal_init.c b/drivers/staging/rtl8712/hal_init.c
index 22974277afa0..4eff3fdecdb8 100644
--- a/drivers/staging/rtl8712/hal_init.c
+++ b/drivers/staging/rtl8712/hal_init.c
@@ -29,21 +29,31 @@
#define FWBUFF_ALIGN_SZ 512
#define MAX_DUMP_FWSZ (48 * 1024)
+static void rtl871x_load_fw_fail(struct _adapter *adapter)
+{
+ struct usb_device *udev = adapter->dvobjpriv.pusbdev;
+ struct device *dev = &udev->dev;
+ struct device *parent = dev->parent;
+
+ complete(&adapter->rtl8712_fw_ready);
+
+ dev_err(&udev->dev, "r8712u: Firmware request failed\n");
+
+ if (parent)
+ device_lock(parent);
+
+ device_release_driver(dev);
+
+ if (parent)
+ device_unlock(parent);
+}
+
static void rtl871x_load_fw_cb(const struct firmware *firmware, void *context)
{
struct _adapter *adapter = context;
if (!firmware) {
- struct usb_device *udev = adapter->dvobjpriv.pusbdev;
- struct usb_interface *usb_intf = adapter->pusb_intf;
-
- dev_err(&udev->dev, "r8712u: Firmware request failed\n");
- usb_put_dev(udev);
- usb_set_intfdata(usb_intf, NULL);
- r8712_free_drv_sw(adapter);
- adapter->dvobj_deinit(adapter);
- complete(&adapter->rtl8712_fw_ready);
- free_netdev(adapter->pnetdev);
+ rtl871x_load_fw_fail(adapter);
return;
}
adapter->fw = firmware;
diff --git a/drivers/staging/rtl8712/usb_intf.c b/drivers/staging/rtl8712/usb_intf.c
index 643f21eb1128..505ebeb643dc 100644
--- a/drivers/staging/rtl8712/usb_intf.c
+++ b/drivers/staging/rtl8712/usb_intf.c
@@ -591,36 +591,30 @@ static void r871xu_dev_remove(struct usb_interface *pusb_intf)
{
struct net_device *pnetdev = usb_get_intfdata(pusb_intf);
struct usb_device *udev = interface_to_usbdev(pusb_intf);
+ struct _adapter *padapter = netdev_priv(pnetdev);
+
+ /* never exit with a firmware callback pending */
+ wait_for_completion(&padapter->rtl8712_fw_ready);
+ usb_set_intfdata(pusb_intf, NULL);
+ release_firmware(padapter->fw);
+ if (drvpriv.drv_registered)
+ padapter->surprise_removed = true;
+ if (pnetdev->reg_state != NETREG_UNINITIALIZED)
+ unregister_netdev(pnetdev); /* will call netdev_close() */
+ r8712_flush_rwctrl_works(padapter);
+ r8712_flush_led_works(padapter);
+ udelay(1);
+ /* Stop driver mlme relation timer */
+ r8712_stop_drv_timers(padapter);
+ r871x_dev_unload(padapter);
+ r8712_free_drv_sw(padapter);
+ free_netdev(pnetdev);
+
+ /* decrease the reference count of the usb device structure
+ * when disconnect
+ */
+ usb_put_dev(udev);
- if (pnetdev) {
- struct _adapter *padapter = netdev_priv(pnetdev);
-
- /* never exit with a firmware callback pending */
- wait_for_completion(&padapter->rtl8712_fw_ready);
- pnetdev = usb_get_intfdata(pusb_intf);
- usb_set_intfdata(pusb_intf, NULL);
- if (!pnetdev)
- goto firmware_load_fail;
- release_firmware(padapter->fw);
- if (drvpriv.drv_registered)
- padapter->surprise_removed = true;
- if (pnetdev->reg_state != NETREG_UNINITIALIZED)
- unregister_netdev(pnetdev); /* will call netdev_close() */
- r8712_flush_rwctrl_works(padapter);
- r8712_flush_led_works(padapter);
- udelay(1);
- /* Stop driver mlme relation timer */
- r8712_stop_drv_timers(padapter);
- r871x_dev_unload(padapter);
- r8712_free_drv_sw(padapter);
- free_netdev(pnetdev);
-
- /* decrease the reference count of the usb device structure
- * when disconnect
- */
- usb_put_dev(udev);
- }
-firmware_load_fail:
/* If we didn't unplug usb dongle and remove/insert module, driver
* fails on sitesurvey for the first time when device is up.
* Reset usb port for sitesurvey fail issue.
--
2.32.0