mmc: core: fix possible use after free of host

BugLink: https://bugs.launchpad.net/bugs/1863019
[ Upstream commit 8e1943af2986db42bee2b8dddf49a36cdb2e9219 ]

In the function mmc_alloc_host, the function put_device is called to
release allocated resources when mmc_gpio_alloc fails. Finally, the
function pointed by host->class_dev.class->dev_release (i.e.,
mmc_host_classdev_release) is used to release resources including the
host structure. However, after put_device, host is used and released
again. Resulting in a use-after-free bug.

Fixes: 1ed217194488 ("mmc: core: fix error path in mmc_host_alloc")
Signed-off-by: Pan Bian <bianpan2016@163.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index 64b03d6eaf184a30c133440299f5820943c8b2bf..076935ff7ce03a203710da45b5e5a2778f934c9e 100644 (file)
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -380,8 +380,6 @@ struct mmc_host *mmc_alloc_host(int extra, struct device *dev)
 
        if (mmc_gpio_alloc(host)) {
                put_device(&host->class_dev);
-               ida_simple_remove(&mmc_host_ida, host->index);
-               kfree(host);
                return NULL;
        }