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Subject[PATCH v1 1/1] firmware_loader: Fix use-after-free during unregister
Date
In the following code within firmware_upload_unregister(), the call
to device_unregister() results in the dev_release function freeing the
fw_upload_priv structure before it is dereferenced for the call to
module_put():

device_unregister(&fw_sysfs->dev);
module_put(fw_upload_priv->module);

This is fixed by copying fw_upload_priv->module to a local variable
before calling device_unregister() and then using the local variable
for the call to module_put().

Reported-by: kernel test robot <oliver.sang@intel.com>
Fixes: 97730bbb242c (firmware_loader: Add firmware-upload support)
Signed-off-by: Russ Weight <russell.h.weight@intel.com>
---
drivers/base/firmware_loader/sysfs_upload.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/base/firmware_loader/sysfs_upload.c b/drivers/base/firmware_loader/sysfs_upload.c
index 87044d52322a..63e15bddd80c 100644
--- a/drivers/base/firmware_loader/sysfs_upload.c
+++ b/drivers/base/firmware_loader/sysfs_upload.c
@@ -377,6 +377,7 @@ void firmware_upload_unregister(struct fw_upload *fw_upload)
{
struct fw_sysfs *fw_sysfs = fw_upload->priv;
struct fw_upload_priv *fw_upload_priv = fw_sysfs->fw_upload_priv;
+ struct module *module = fw_upload_priv->module;

mutex_lock(&fw_upload_priv->lock);
if (fw_upload_priv->progress == FW_UPLOAD_PROG_IDLE) {
@@ -392,6 +393,6 @@ void firmware_upload_unregister(struct fw_upload *fw_upload)

unregister:
device_unregister(&fw_sysfs->dev);
- module_put(fw_upload_priv->module);
+ module_put(module);
}
EXPORT_SYMBOL_GPL(firmware_upload_unregister);
--
2.25.1
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