5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Paul Durrant <pdurrant@xxxxxxxxxx>
[ 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@xxxxxxxx>
Signed-off-by: Paul Durrant <pdurrant@xxxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Stable-dep-of: afc545da381b ("xen: Fix the issue of resource not being properly released in xenbus_dev_probe()")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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);
--
2.43.0
