[PATCH] RLIMIT_MEMLOCK checking fix

Always use page counts when doing RLIMIT_MEMLOCK checking to avoid possible
overflow.
Signed-off-by: NChris Wright <chrisw@osdl.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

mm/mmap.c

@@ -937,9 +937,10 @@ unsigned long do_mmap_pgoff(struct file * file, unsigned long addr,
 	/* mlock MCL_FUTURE? */
 	if (vm_flags & VM_LOCKED) {
 		unsigned long locked, lock_limit;
-		locked = mm->locked_vm << PAGE_SHIFT;
+		locked = len >> PAGE_SHIFT;
+		locked += mm->locked_vm;
 		lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
-		locked += len;
+		lock_limit >>= PAGE_SHIFT;
 		if (locked > lock_limit && !capable(CAP_IPC_LOCK))
 			return -EAGAIN;
 	}
@@ -1822,9 +1823,10 @@ unsigned long do_brk(unsigned long addr, unsigned long len)
 	 */
 	if (mm->def_flags & VM_LOCKED) {
 		unsigned long locked, lock_limit;
-		locked = mm->locked_vm << PAGE_SHIFT;
+		locked = len >> PAGE_SHIFT;
+		locked += mm->locked_vm;
 		lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
-		locked += len;
+		lock_limit >>= PAGE_SHIFT;
 		if (locked > lock_limit && !capable(CAP_IPC_LOCK))
 			return -EAGAIN;
 	}