The violation of atomicity occurs when the brbd_uuid_set_bm function is
executed simultaneously with modifying the value of
device->ldev->md.uuid[UI_BITMAP]. Consider a scenario where, while
device->ldev->md.uuid[UI_BITMAP] passes the validity check when its value
is not zero, the value of device->ldev->md.uuid[UI_BITMAP] is written to
zero. In this case, the check in brbd_uuid_set_bm might refer to the old
value of device->ldev->md.uuid[UI_BITMAP] (before locking), which allows
an invalid value to pass the validity check, resulting in inconsistency.
To address this issue, it is recommended to include the data validity check
within the locked section of the function. This modification ensures that
the value of device->ldev->md.uuid[UI_BITMAP] does not change during the
validation process, thereby maintaining its integrity.
This possible bug is found by an experimental static analysis tool
developed by our team. This tool analyzes the locking APIs to extract
function pairs that can be concurrently executed, and then analyzes the
instructions in the paired functions to identify possible concurrency bugs
including data races and atomicity violations.
Fixes: 9f2247bb9b75 ("drbd: Protect accesses to the uuid set with a spinlock")
Cc: stable(a)vger.kernel.org
Signed-off-by: Qiu-ji Chen <chenqiuji666(a)gmail.com>
---
drivers/block/drbd/drbd_main.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index a9e49b212341..abafc4edf9ed 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -3399,10 +3399,12 @@ void drbd_uuid_new_current(struct drbd_device *device) __must_hold(local)
void drbd_uuid_set_bm(struct drbd_device *device, u64 val) __must_hold(local)
{
unsigned long flags;
- if (device->ldev->md.uuid[UI_BITMAP] == 0 && val == 0)
+ spin_lock_irqsave(&device->ldev->md.uuid_lock, flags);
+ if (device->ldev->md.uuid[UI_BITMAP] == 0 && val == 0) {
+ spin_unlock_irqrestore(&device->ldev->md.uuid_lock, flags);
return;
+ }
- spin_lock_irqsave(&device->ldev->md.uuid_lock, flags);
if (val == 0) {
drbd_uuid_move_history(device);
device->ldev->md.uuid[UI_HISTORY_START] = device->ldev->md.uuid[UI_BITMAP];
--
2.34.1
As we process the second byte of a control transfer, transfers
of less than 2 bytes must be discarded.
This bug is as old as the driver.
SIgned-off-by: Oliver Neukum <oneukum(a)suse.com>
CC: stable(a)vger.kernel.org
---
drivers/usb/misc/cypress_cy7c63.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/usb/misc/cypress_cy7c63.c b/drivers/usb/misc/cypress_cy7c63.c
index cecd7693b741..75f5a740cba3 100644
--- a/drivers/usb/misc/cypress_cy7c63.c
+++ b/drivers/usb/misc/cypress_cy7c63.c
@@ -88,6 +88,9 @@ static int vendor_command(struct cypress *dev, unsigned char request,
USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_OTHER,
address, data, iobuf, CYPRESS_MAX_REQSIZE,
USB_CTRL_GET_TIMEOUT);
+ /* we must not process garbage */
+ if (retval < 2)
+ goto err_buf;
/* store returned data (more READs to be added) */
switch (request) {
@@ -107,6 +110,7 @@ static int vendor_command(struct cypress *dev, unsigned char request,
break;
}
+err_buf:
kfree(iobuf);
error:
return retval;
--
2.45.2
There is a small window during probing when IO is running
but the backlight is not registered. Processing events
during that time will crash. The completion handler
needs to check for a backlight before scheduling work.
The bug is as old as the driver.
Signed-off-by: Oliver Neukum <oneukum(a)suse.com>
CC: stable(a)vger.kernel.org
---
drivers/usb/misc/appledisplay.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/drivers/usb/misc/appledisplay.c b/drivers/usb/misc/appledisplay.c
index c8098e9b432e..62b5a30edc42 100644
--- a/drivers/usb/misc/appledisplay.c
+++ b/drivers/usb/misc/appledisplay.c
@@ -107,7 +107,12 @@ static void appledisplay_complete(struct urb *urb)
case ACD_BTN_BRIGHT_UP:
case ACD_BTN_BRIGHT_DOWN:
pdata->button_pressed = 1;
- schedule_delayed_work(&pdata->work, 0);
+ /*
+ * there is a window during which no device
+ * is registered
+ */
+ if (pdata->bd )
+ schedule_delayed_work(&pdata->work, 0);
break;
case ACD_BTN_NONE:
default:
@@ -202,6 +207,7 @@ static int appledisplay_probe(struct usb_interface *iface,
const struct usb_device_id *id)
{
struct backlight_properties props;
+ struct backlight_device *backlight;
struct appledisplay *pdata;
struct usb_device *udev = interface_to_usbdev(iface);
struct usb_endpoint_descriptor *endpoint;
@@ -272,13 +278,14 @@ static int appledisplay_probe(struct usb_interface *iface,
memset(&props, 0, sizeof(struct backlight_properties));
props.type = BACKLIGHT_RAW;
props.max_brightness = 0xff;
- pdata->bd = backlight_device_register(bl_name, NULL, pdata,
+ backlight = backlight_device_register(bl_name, NULL, pdata,
&appledisplay_bl_data, &props);
- if (IS_ERR(pdata->bd)) {
+ if (IS_ERR(backlight)) {
dev_err(&iface->dev, "Backlight registration failed\n");
- retval = PTR_ERR(pdata->bd);
+ retval = PTR_ERR(backlight);
goto error;
}
+ pdata->bd = backlight;
/* Try to get brightness */
brightness = appledisplay_bl_get_brightness(pdata->bd);
--
2.45.2