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

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From: chenjie <chenjie6@huawei.com>

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

Signed-off-by: chenjie <chenjie6@huawei.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

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[PATCH] memory:bugxfix panic on cat or write /dev/kmem <chenjie6@huawei.com> - 2016-06-23 11:30 +0200
  Re: [PATCH] memory:bugxfix panic on cat or write /dev/kmem Michal Hocko <mhocko@kernel.org> - 2016-06-23 14:50 +0200
    Re: [PATCH] memory:bugxfix panic on cat or write /dev/kmem "Chenjie (K)" <chenjie6@huawei.com> - 2016-06-25 03:30 +0200
      Re: [PATCH] memory:bugxfix panic on cat or write /dev/kmem Michal Hocko <mhocko@kernel.org> - 2016-06-27 13:40 +0200

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