proc: mem_release() should check mm != NULL
mem_release() can hit mm == NULL, add the necessary check.
Cc: stable@kernel.org
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 9cde9edf..c3617ea 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -822,8 +822,8 @@
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;
}