From: Lai Jiangshan <jiangshan.ljs(a)antgroup.com>
Marc Hartmayer reported:
[ 23.133876] Unable to handle kernel pointer dereference in virtual kernel address space
[ 23.133950] Failing address: 0000000000000000 TEID: 0000000000000483
[ 23.133954] Fault in home space mode while using kernel ASCE.
[ 23.133957] AS:000000001b8f0007 R3:0000000056cf4007 S:0000000056cf3800 P:000000000000003d
[ 23.134207] Oops: 0004 ilc:2 [#1] SMP
(snip)
[ 23.134516] Call Trace:
[ 23.134520] [<0000024e326caf28>] worker_thread+0x48/0x430
[ 23.134525] ([<0000024e326caf18>] worker_thread+0x38/0x430)
[ 23.134528] [<0000024e326d3a3e>] kthread+0x11e/0x130
[ 23.134533] [<0000024e3264b0dc>] __ret_from_fork+0x3c/0x60
[ 23.134536] [<0000024e333fb37a>] ret_from_fork+0xa/0x38
[ 23.134552] Last Breaking-Event-Address:
[ 23.134553] [<0000024e333f4c04>] mutex_unlock+0x24/0x30
[ 23.134562] Kernel panic - not syncing: Fatal exception: panic_on_oops
With debuging and analysis, worker_thread() accesses to the nullified
worker->pool when the newly created worker is destroyed before being
waken-up, in which case worker_thread() can see the result detach_worker()
reseting worker->pool to NULL at the begining.
Move the code "worker->pool = NULL;" out from detach_worker() to fix the
problem.
worker->pool had been designed to be constant for regular workers and
changeable for rescuer. To share attaching/detaching code for regular
and rescuer workers and to avoid worker->pool being accessed inadvertently
when the worker has been detached, worker->pool is reset to NULL when
detached no matter the worker is rescuer or not.
To maintain worker->pool being reset after detached, move the code
"worker->pool = NULL;" in the worker thread context after detached.
It is either be in the regular worker thread context after PF_WQ_WORKER
is cleared or in rescuer worker thread context with wq_pool_attach_mutex
held. So it is safe to do so.
Cc: Marc Hartmayer <mhartmay(a)linux.ibm.com>
Link: https://lore.kernel.org/lkml/87wmjj971b.fsf@linux.ibm.com/
Reported-by: Marc Hartmayer <mhartmay(a)linux.ibm.com>
Fixes: f4b7b53c94af ("workqueue: Detach workers directly in idle_cull_fn()")
Cc: stable(a)vger.kernel.org # v6.11+
Signed-off-by: Lai Jiangshan <jiangshan.ljs(a)antgroup.com>
---
kernel/workqueue.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index e7b005ff3750..6f2545037e57 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -2709,7 +2709,6 @@ static void detach_worker(struct worker *worker)
unbind_worker(worker);
list_del(&worker->node);
- worker->pool = NULL;
}
/**
@@ -2729,6 +2728,7 @@ static void worker_detach_from_pool(struct worker *worker)
mutex_lock(&wq_pool_attach_mutex);
detach_worker(worker);
+ worker->pool = NULL;
mutex_unlock(&wq_pool_attach_mutex);
/* clear leftover flags without pool->lock after it is detached */
@@ -3349,7 +3349,11 @@ static int worker_thread(void *__worker)
if (unlikely(worker->flags & WORKER_DIE)) {
raw_spin_unlock_irq(&pool->lock);
set_pf_worker(false);
-
+ /*
+ * The worker is dead and PF_WQ_WORKER is cleared, worker->pool
+ * shouldn't be accessed, reset it to NULL in case otherwise.
+ */
+ worker->pool = NULL;
ida_free(&pool->worker_ida, worker->id);
return 0;
}
--
2.19.1.6.gb485710b
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