[PATCH] RLIMIT_AS checking fix

Address bug #4508: there's potential for wraparound in the various places
where we perform RLIMIT_AS checking.

(I'm a bit worried about acct_stack_growth().  Are we sure that vma->vm_mm is
always equal to current->mm?  If not, then we're comparing some other
process's total_vm with the calling process's rlimits).

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

1 files changed, 3 insertions, 3 deletions

diff --git a/mm/mremap.c b/mm/mremap.c
index 0d1c1b9c7a0a..0dd7ace94e51 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -347,10 +347,10 @@ unsigned long do_mremap(unsigned long addr,
                 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
                         goto out;
         }
-        ret = -ENOMEM;
-        if ((current->mm->total_vm << PAGE_SHIFT) + (new_len - old_len)
-            > current->signal->rlim[RLIMIT_AS].rlim_cur)
+        if (!may_expand_vm(current->mm, (new_len - old_len) >> PAGE_SHIFT)) {
+                ret = -ENOMEM;
                 goto out;
+        }
 
         if (vma->vm_flags & VM_ACCOUNT) {
                 charged = (new_len - old_len) >> PAGE_SHIFT;