5.4-stable review patch. If anyone has any objections, please let me know.
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From: Qiu-ji Chen chenqiuji666@gmail.com
[ Upstream commit afc545da381ba0c651b2658966ac737032676f01 ]
This patch fixes an issue in the function xenbus_dev_probe(). In the xenbus_dev_probe() function, within the if (err) branch at line 313, the program incorrectly returns err directly without releasing the resources allocated by err = drv->probe(dev, id). As the return value is non-zero, the upper layers assume the processing logic has failed. However, the probe operation was performed earlier without a corresponding remove operation. Since the probe actually allocates resources, failing to perform the remove operation could lead to problems.
To fix this issue, we followed the resource release logic of the xenbus_dev_remove() function by adding a new block fail_remove before the fail_put block. After entering the branch if (err) at line 313, the function will use a goto statement to jump to the fail_remove block, ensuring that the previously acquired resources are correctly released, thus preventing the reference count leak.
This bug was identified by an experimental static analysis tool developed by our team. The tool specializes in analyzing reference count operations and detecting potential issues where resources are not properly managed. In this case, the tool flagged the missing release operation as a potential problem, which led to the development of this patch.
Fixes: 4bac07c993d0 ("xen: add the Xenbus sysfs and virtual device hotplug driver") Cc: stable@vger.kernel.org Signed-off-by: Qiu-ji Chen chenqiuji666@gmail.com Reviewed-by: Juergen Gross jgross@suse.com Message-ID: 20241105130919.4621-1-chenqiuji666@gmail.com Signed-off-by: Juergen Gross jgross@suse.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/xen/xenbus/xenbus_probe.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c index b88512d92ef52..fd686b962727a 100644 --- a/drivers/xen/xenbus/xenbus_probe.c +++ b/drivers/xen/xenbus/xenbus_probe.c @@ -250,10 +250,16 @@ int xenbus_dev_probe(struct device *_dev) if (err) { dev_warn(&dev->dev, "watch_otherend on %s failed.\n", dev->nodename); - return err; + goto fail_remove; }
return 0; +fail_remove: + if (drv->remove) { + down(&dev->reclaim_sem); + drv->remove(dev); + up(&dev->reclaim_sem); + } fail_put: module_put(drv->driver.owner); fail: