From 401f63716ca0bca1728e55ccf2132fb3785cf5da Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@redhat.com>
Date: Tue, 31 Jan 2012 17:14:38 +0100
Subject: proc: mem_release() should check mm != NULL

commit 71879d3cb3dd8f2dfdefb252775c1b3ea04a3dd4 upstream.

mem_release() can hit mm == NULL, add the necessary check.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/proc/base.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

(limited to 'fs/proc/base.c')

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 7b28f27..b3e298f 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -886,8 +886,8 @@ loff_t mem_lseek(struct file *file, loff_t offset, int orig)
 static int mem_release(struct inode *inode, struct file *file)
 {
 	struct mm_struct *mm = file->private_data;
-
-	mmput(mm);
+	if (mm)
+		mmput(mm);
 	return 0;
 }
 
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