[PATCH 4/6] sysctl: dont overflow the user-supplied buffer with 0

[Chris Wright <chrisw@sous-sol.org>]

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

If the string was too long to fit in the user-supplied buffer,
the sysctl layer would zero-terminate it by writing past the
end of the buffer. Don't do that.

Noticed by Yi Yang <yang.y.yi@gmail.com>

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
 kernel/sysctl.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

--- linux-2.6.14.5.orig/kernel/sysctl.c
+++ linux-2.6.14.5/kernel/sysctl.c
@@ -2200,14 +2200,12 @@ int sysctl_string(ctl_table *table, int 
 		if (get_user(len, oldlenp))
 			return -EFAULT;
 		if (len) {
-			l = strlen(table->data);
+			l = strlen(table->data)+1;
 			if (len > l) len = l;
 			if (len >= table->maxlen)
 				len = table->maxlen;
 			if(copy_to_user(oldval, table->data, len))
 				return -EFAULT;
-			if(put_user(0, ((char __user *) oldval) + len))
-				return -EFAULT;
 			if(put_user(len, oldlenp))
 				return -EFAULT;
 		}

--
-
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