linux-kernel - [PATCH] dma-buf: Fix memory leak in dma_buf_set

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Date:   Fri, 16 Aug 2019 23:30:22 +0530
From:   Bharath Vedartham <linux.bhar@...il.com>
To:     sumit.semwal@...aro.org
Cc:     linux-media@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linaro-mm-sig@...ts.linaro.org, linux-kernel@...r.kernel.org,
        Bharath Vedartham <linux.bhar@...il.com>
Subject: [PATCH] dma-buf: Fix memory leak in dma_buf_set_name

This patch fixes a memory leak bug reported by syzbot. Link to the
bug is given at [1].

A local variable name is used to hold the copied user buffer string
using strndup_user. strndup_user allocates memory using
kmalloc_track_caller in memdup_user. This kmalloc allocation needs to be
followed by a kfree.

This patch has been tested by a compile test.

[1] https://syzkaller.appspot.com/bug?id=ce692a3aa13e00e335e090be7846c6eb60ddff7a

Reported-by: syzbot+b2098bc44728a4efb3e9@...kaller.appspotmail.com
Signed-off-by: Bharath Vedartham <linux.bhar@...il.com>
---
 drivers/dma-buf/dma-buf.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index f45bfb2..9798f6d 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -342,6 +342,7 @@ static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf)
 	}
 	kfree(dmabuf->name);
 	dmabuf->name = name;
+	kfree(name);
 
 out_unlock:
 	mutex_unlock(&dmabuf->lock);
-- 
2.7.4