[PATCH 4.19 351/639] mmc: core: fix possible use after free of host

[Greg Kroah-Hartman]

From: Pan Bian <bianpan2016@xxxxxxx>

[ 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@xxxxxxx>
Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/mmc/core/host.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index f57f5de542064..dd1c14d8f6863 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -385,8 +385,6 @@ 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;
 	}
 
-- 
2.20.1