[PATCH] RLIMIT_MEMLOCK checking fix

Always use page counts when doing RLIMIT_MEMLOCK checking to avoid possible
overflow.

Signed-off-by: Chris Wright <chrisw@osdl.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 6 insertions, 4 deletions

diff --git a/mm/mmap.c b/mm/mmap.c
index 1ec0f6e9c0d8..01f9793591f6 100644
--- a/mm/mmap.c
+++ b/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;
         }