[PATCH 4.9 28/70] uio: potential double frees if __uio_register_device() fails

Greg Kroah-Hartman
2018-09-17T22:53:59Z

From: Dan Carpenter <dan.carpenter@oracle.com>

[ Upstream commit f019f07ecf6a6b8bd6d7853bce70925d90af02d1 ]

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@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/uio/uio.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -841,8 +841,6 @@ 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)) {
/*
* Note that we deliberately don't use devm_request_irq
@@ -858,6 +856,7 @@ int __uio_register_device(struct module
goto err_request_irq;
}

+ info->uio_dev = idev;
return 0;