5.4-stable review patch. If anyone has any objections, please let me know.
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From: Paul Durrant pdurrant@amazon.com
[ Upstream commit 196748a276b4dee01177e6b7abcda27cd759de83 ]
To prevent a PV driver module being removed whilst attached to its other end, and hence xenbus calling into potentially invalid text, take a reference on the module before calling the probe() method (dropping it if unsuccessful) and drop the reference after returning from the remove() method.
Suggested-by: Jan Beulich jbeulich@suse.com Signed-off-by: Paul Durrant pdurrant@amazon.com Reviewed-by: Jan Beulich jbeulich@suse.com Reviewed-by: Juergen Gross jgross@suse.com Signed-off-by: Juergen Gross jgross@suse.com Stable-dep-of: afc545da381b ("xen: Fix the issue of resource not being properly released in xenbus_dev_probe()") Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/xen/xenbus/xenbus_probe.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c index b911a91bce6b7..9215099caad61 100644 --- a/drivers/xen/xenbus/xenbus_probe.c +++ b/drivers/xen/xenbus/xenbus_probe.c @@ -233,9 +233,16 @@ int xenbus_dev_probe(struct device *_dev) return err; }
+ if (!try_module_get(drv->driver.owner)) { + dev_warn(&dev->dev, "failed to acquire module reference on '%s'\n", + drv->driver.name); + err = -ESRCH; + goto fail; + } + err = drv->probe(dev, id); if (err) - goto fail; + goto fail_put;
err = watch_otherend(dev); if (err) { @@ -245,6 +252,8 @@ int xenbus_dev_probe(struct device *_dev) }
return 0; +fail_put: + module_put(drv->driver.owner); fail: xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename); xenbus_switch_state(dev, XenbusStateClosed); @@ -264,6 +273,8 @@ int xenbus_dev_remove(struct device *_dev) if (drv->remove) drv->remove(dev);
+ module_put(drv->driver.owner); + free_otherend_details(dev);
xenbus_switch_state(dev, XenbusStateClosed);