linux-kernel - [PATCH] memory:bugxfix panic on cat or write /dev/kmem

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Message-ID: <1466703010-32242-1-git-send-email-chenjie6@huawei.com>
Date:	Fri, 24 Jun 2016 01:30:10 +0800
From:	<chenjie6@...wei.com>
To:	<linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
	<David.Woodhouse@...el.com>, <zhihui.gao@...wei.com>,
	<panxuesong@...wei.com>
CC:	<akpm@...ux-foundation.org>, chenjie <chenjie6@...wei.com>
Subject: [PATCH] memory:bugxfix panic on cat or write /dev/kmem

From: chenjie <chenjie6@...wei.com>

cat /dev/kmem and echo > /dev/kmem will lead panic

Signed-off-by: chenjie <chenjie6@...wei.com>
---
 drivers/char/mem.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 71025c2..4bdde28 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -412,6 +412,8 @@ static ssize_t read_kmem(struct file *file, char __user *buf,
 			 * by the kernel or data corruption may occur
 			 */
 			kbuf = xlate_dev_kmem_ptr((void *)p);
+			if (!kbuf)
+				return -EFAULT;
 
 			if (copy_to_user(buf, kbuf, sz))
 				return -EFAULT;
@@ -482,6 +484,11 @@ static ssize_t do_write_kmem(unsigned long p, const char __user *buf,
 		 * corruption may occur.
 		 */
 		ptr = xlate_dev_kmem_ptr((void *)p);
+		if (!ptr) {
+			if (written)
+				break;
+			return -EFAULT;
+		}
 
 		copied = copy_from_user(ptr, buf, sz);
 		if (copied) {
-- 
1.8.0