Re: rlimit_as-checking-fix.patch

[Chris Wright <chrisw@osdl.org>]

* Andrew Morton (akpm@osdl.org) wrote:
> Andrew Morton <akpm@osdl.org> wrote:
> >
> > review, please?
> 
> crappy reviewers.  Tested version.

Sorry to be so slow on that one.  Here's an update for the mlock part.
It's only compile tested as of yet.




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

Signed-off-by: Chris Wright <chrisw@osdl.org>
---

mm/mmap.c: 6ea204cc751e4d2f0fe4a7d213bab9ae90ad58c4
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -937,9 +937,10 @@ unsigned long do_mmap_pgoff(struct file 
 	/* 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;
 	}
@@ -1823,9 +1824,10 @@ unsigned long do_brk(unsigned long addr,
 	 */
 	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;
 	}
--
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