[PATCH 3.16 095/328] uio: potential double frees if __uio_register_device() fails

From: Ben Hutchings
Date: Sun Dec 09 2018 - 17:26:13 EST

3.16.62-rc1 review patch. If anyone has any objections, please let me know.


From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

commit f019f07ecf6a6b8bd6d7853bce70925d90af02d1 upstream.

The uio_unregister_device() function assumes that if "info->uio_dev" is
non-NULL that means "info" is fully allocated. Setting info->uio_de
has to be the last thing in the function.

In the current code, if request_threaded_irq() fails then we return with
info->uio_dev set to non-NULL but info is not fully allocated and it can
lead to double frees.

Fixes: beafc54c4e2f ("UIO: Add the User IO core code")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
drivers/uio/uio.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -852,8 +852,6 @@ int __uio_register_device(struct module
if (ret)
goto err_uio_dev_add_attributes;

- info->uio_dev = idev;
if (info->irq && (info->irq != UIO_IRQ_CUSTOM)) {
ret = devm_request_irq(idev->dev, info->irq, uio_interrupt,
info->irq_flags, info->name, idev);
@@ -861,6 +859,7 @@ int __uio_register_device(struct module
goto err_request_irq;

+ info->uio_dev = idev;
return 0;