uio: potential double frees if __uio_register_device() fails

BugLink: https://bugs.launchpad.net/bugs/1836117
[ 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>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index ff04b7f8549f06f5730afb1cf6334785afab9d05..41784798c789b9dd1c1bffbd80920e346ea283a3 100644 (file)
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -841,8 +841,6 @@ int __uio_register_device(struct module *owner,
        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 *owner,
                        goto err_request_irq;
        }
 
+       info->uio_dev = idev;
        return 0;
 
 err_request_irq: