Merge tag 'v3.10.108' into update

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / fs / exec.c

diff --git a/fs/exec.c b/fs/exec.c
index fb7cf78c355ec04d7b4d131ad6697107b2e1d566..ae2718e540f15d3875a5312113e2ea64aabee833 100644 (file)
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -196,8 +196,26 @@ static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 
        if (write) {
                unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
+               unsigned long ptr_size;
                struct rlimit *rlim;
 
+               /*
+                * Since the stack will hold pointers to the strings, we
+                * must account for them as well.
+                *
+                * The size calculation is the entire vma while each arg page is
+                * built, so each time we get here it's calculating how far it
+                * is currently (rather than each call being just the newly
+                * added size from the arg page).  As a result, we need to
+                * always add the entire size of the pointers, so that on the
+                * last call to get_arg_page() we'll actually have the entire
+                * correct size.
+                */
+               ptr_size = (bprm->argc + bprm->envc) * sizeof(void *);
+               if (ptr_size > ULONG_MAX - size)
+                       goto fail;
+               size += ptr_size;
+
                acct_arg_size(bprm, size / PAGE_SIZE);
 
                /*
@@ -215,13 +233,15 @@ static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
                 *    to work from.
                 */
                rlim = current->signal->rlim;
-               if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
-                       put_page(page);
-                       return NULL;
-               }
+               if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4)
+                       goto fail;
        }
 
        return page;
+
+fail:
+       put_page(page);
+       return NULL;
 }
 
 static void put_arg_page(struct page *page)