1 files changed, 20 insertions, 95 deletions

diff --git a/fs/exec.c b/fs/exec.c
index 50e76cc633c4..6c53920795c2 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -145,13 +145,11 @@ SYSCALL_DEFINE1(uselib, const char __user *, library)
 		goto out;
 
 	/*
-	 * may_open() has already checked for this, so it should be
-	 * impossible to trip now. But we need to be extra cautious
-	 * and check again at the very end too.
+	 * Check do_open_execat() for an explanation.
 	 */
 	error = -EACCES;
-	if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) ||
-			 path_noexec(&file->f_path)))
+	if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode)) ||
+	    path_noexec(&file->f_path))
 		goto exit;
 
 	error = -ENOEXEC;
@@ -712,80 +710,6 @@ static int copy_strings_kernel(int argc, const char *const *argv,
 #ifdef CONFIG_MMU
 
 /*
- * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
- * the binfmt code determines where the new stack should reside, we shift it to
- * its final location.  The process proceeds as follows:
- *
- * 1) Use shift to calculate the new vma endpoints.
- * 2) Extend vma to cover both the old and new ranges.  This ensures the
- *    arguments passed to subsequent functions are consistent.
- * 3) Move vma's page tables to the new range.
- * 4) Free up any cleared pgd range.
- * 5) Shrink the vma to cover only the new range.
- */
-static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
-{
-	struct mm_struct *mm = vma->vm_mm;
-	unsigned long old_start = vma->vm_start;
-	unsigned long old_end = vma->vm_end;
-	unsigned long length = old_end - old_start;
-	unsigned long new_start = old_start - shift;
-	unsigned long new_end = old_end - shift;
-	VMA_ITERATOR(vmi, mm, new_start);
-	struct vm_area_struct *next;
-	struct mmu_gather tlb;
-
-	BUG_ON(new_start > new_end);
-
-	/*
-	 * ensure there are no vmas between where we want to go
-	 * and where we are
-	 */
-	if (vma != vma_next(&vmi))
-		return -EFAULT;
-
-	vma_iter_prev_range(&vmi);
-	/*
-	 * cover the whole range: [new_start, old_end)
-	 */
-	if (vma_expand(&vmi, vma, new_start, old_end, vma->vm_pgoff, NULL))
-		return -ENOMEM;
-
-	/*
-	 * move the page tables downwards, on failure we rely on
-	 * process cleanup to remove whatever mess we made.
-	 */
-	if (length != move_page_tables(vma, old_start,
-				       vma, new_start, length, false, true))
-		return -ENOMEM;
-
-	lru_add_drain();
-	tlb_gather_mmu(&tlb, mm);
-	next = vma_next(&vmi);
-	if (new_end > old_start) {
-		/*
-		 * when the old and new regions overlap clear from new_end.
-		 */
-		free_pgd_range(&tlb, new_end, old_end, new_end,
-			next ? next->vm_start : USER_PGTABLES_CEILING);
-	} else {
-		/*
-		 * otherwise, clean from old_start; this is done to not touch
-		 * the address space in [new_end, old_start) some architectures
-		 * have constraints on va-space that make this illegal (IA64) -
-		 * for the others its just a little faster.
-		 */
-		free_pgd_range(&tlb, old_start, old_end, new_end,
-			next ? next->vm_start : USER_PGTABLES_CEILING);
-	}
-	tlb_finish_mmu(&tlb);
-
-	vma_prev(&vmi);
-	/* Shrink the vma to just the new range */
-	return vma_shrink(&vmi, vma, new_start, new_end, vma->vm_pgoff);
-}
-
-/*
  * Finalizes the stack vm_area_struct. The flags and permissions are updated,
  * the stack is optionally relocated, and some extra space is added.
  */
@@ -813,7 +737,8 @@ int setup_arg_pages(struct linux_binprm *bprm,
 	stack_base = calc_max_stack_size(stack_base);
 
 	/* Add space for stack randomization. */
-	stack_base += (STACK_RND_MASK << PAGE_SHIFT);
+	if (current->flags & PF_RANDOMIZE)
+		stack_base += (STACK_RND_MASK << PAGE_SHIFT);
 
 	/* Make sure we didn't let the argument array grow too large. */
 	if (vma->vm_end - vma->vm_start > stack_base)
@@ -877,7 +802,12 @@ int setup_arg_pages(struct linux_binprm *bprm,
 
 	/* Move stack pages down in memory. */
 	if (stack_shift) {
-		ret = shift_arg_pages(vma, stack_shift);
+		/*
+		 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
+		 * the binfmt code determines where the new stack should reside, we shift it to
+		 * its final location.
+		 */
+		ret = relocate_vma_down(vma, stack_shift);
 		if (ret)
 			goto out_unlock;
 	}
@@ -954,7 +884,6 @@ EXPORT_SYMBOL(transfer_args_to_stack);
 static struct file *do_open_execat(int fd, struct filename *name, int flags)
 {
 	struct file *file;
-	int err;
 	struct open_flags open_exec_flags = {
 		.open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
 		.acc_mode = MAY_EXEC,
@@ -971,24 +900,20 @@ static struct file *do_open_execat(int fd, struct filename *name, int flags)
 
 	file = do_filp_open(fd, name, &open_exec_flags);
 	if (IS_ERR(file))
-		goto out;
+		return file;
 
 	/*
-	 * may_open() has already checked for this, so it should be
-	 * impossible to trip now. But we need to be extra cautious
-	 * and check again at the very end too.
+	 * In the past the regular type check was here. It moved to may_open() in
+	 * 633fb6ac3980 ("exec: move S_ISREG() check earlier"). Since then it is
+	 * an invariant that all non-regular files error out before we get here.
 	 */
-	err = -EACCES;
-	if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) ||
-			 path_noexec(&file->f_path)))
-		goto exit;
+	if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode)) ||
+	    path_noexec(&file->f_path)) {
+		fput(file);
+		return ERR_PTR(-EACCES);
+	}
 
-out:
 	return file;
-
-exit:
-	fput(file);
-	return ERR_PTR(err);
 }
 
 /**