linux-kernel - [PATCH AUTOSEL 4.19 336/671] mmc: core: fix possible use after free of host

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Date:   Thu, 16 Jan 2020 11:59:34 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Pan Bian <bianpan2016@....com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Sasha Levin <sashal@...nel.org>, linux-mmc@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 336/671] mmc: core: fix possible use after free of host

From: Pan Bian <bianpan2016@....com>

[ 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@....com>
Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 f57f5de54206..dd1c14d8f686 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