linux-kernel - [PATCH 4.19 174/220] media: isif: fix a NULL pointer dereference bug

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Message-Id: <20191122100925.367404978@linuxfoundation.org>
Date:   Fri, 22 Nov 2019 11:28:59 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Wenwen Wang <wang6495@....edu>,
        Hans Verkuil <hverkuil@...all.nl>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 174/220] media: isif: fix a NULL pointer dereference bug

From: Wenwen Wang <wang6495@....edu>

[ Upstream commit a26ac6c1bed951b2066cc4b2257facd919e35c0b ]

In isif_probe(), there is a while loop to get the ISIF base address and
linearization table0 and table1 address. In the loop body, the function
platform_get_resource() is called to get the resource. If
platform_get_resource() returns NULL, the loop is terminated and the
execution goes to 'fail_nobase_res'. Suppose the loop is terminated at the
first iteration because platform_get_resource() returns NULL and the
execution goes to 'fail_nobase_res'. Given that there is another while loop
at 'fail_nobase_res' and i equals to 0, one iteration of the second while
loop will be executed. However, the second while loop does not check the
return value of platform_get_resource(). This can cause a NULL pointer
dereference bug if the return value is a NULL pointer.

This patch avoids the above issue by adding a check in the second while
loop after the call to platform_get_resource().

Signed-off-by: Wenwen Wang <wang6495@....edu>
Signed-off-by: Hans Verkuil <hverkuil@...all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/media/platform/davinci/isif.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/media/platform/davinci/isif.c b/drivers/media/platform/davinci/isif.c
index f924e76e2fbf8..340f8218f54d3 100644
--- a/drivers/media/platform/davinci/isif.c
+++ b/drivers/media/platform/davinci/isif.c
@@ -1100,7 +1100,8 @@ static int isif_probe(struct platform_device *pdev)

 	while (i >= 0) {
 		res = platform_get_resource(pdev, IORESOURCE_MEM, i);
-		release_mem_region(res->start, resource_size(res));
+		if (res)
+			release_mem_region(res->start, resource_size(res));
 		i--;
 	}
 	vpfe_unregister_ccdc_device(&isif_hw_dev);
-- 
2.20.1