3.8.13.13 -stable review patch.  If anyone has any objections, please let me 
know.

------------------

From: Dan Carpenter <[email protected]>

commit 201f99f170df14ba52ea4c52847779042b7a623b upstream.

We don't cap the size of buffer from the user so we could write past the
end of the array here.  Only root can write to this file.

Reported-by: Nico Golde <[email protected]>
Reported-by: Fabian Yamaguchi <[email protected]>
Signed-off-by: Dan Carpenter <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Kamal Mostafa <[email protected]>
---
 arch/um/kernel/exitcode.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/um/kernel/exitcode.c b/arch/um/kernel/exitcode.c
index 829df49..41ebbfe 100644
--- a/arch/um/kernel/exitcode.c
+++ b/arch/um/kernel/exitcode.c
@@ -40,9 +40,11 @@ static ssize_t exitcode_proc_write(struct file *file,
                const char __user *buffer, size_t count, loff_t *pos)
 {
        char *end, buf[sizeof("nnnnn\0")];
+       size_t size;
        int tmp;
 
-       if (copy_from_user(buf, buffer, count))
+       size = min(count, sizeof(buf));
+       if (copy_from_user(buf, buffer, size))
                return -EFAULT;
 
        tmp = simple_strtol(buf, &end, 0);
-- 
1.8.1.2

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