linux-kernel - [PATCH] mm: mmap: Check all failures before set values

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Message-ID: <COL130-W55CFB40ACE11D2A0083E04B9630@phx.gbl>
Date:	Mon, 24 Aug 2015 01:21:52 +0800
From:	Chen Gang <xili_gchen_5257@...mail.com>
To:	kernel mailing list <linux-kernel@...r.kernel.org>,
	"linux-ia64@...r.kernel.org" <linux-ia64@...r.kernel.org>
Subject: [PATCH] mm: mmap: Check all failures before set values

When failure occurs and return, vma->vm_pgoff is already set, which is
not a good idea.

Signed-off-by: Chen Gang <gang.chen.5i5j@...il.com>
---
 mm/mmap.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 8e0366e..b5a6f09 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2878,6 +2878,13 @@ int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
 	struct vm_area_struct *prev;
 	struct rb_node **rb_link, *rb_parent;
 
+	if (find_vma_links(mm, vma->vm_start, vma->vm_end,
+			   &prev, &rb_link, &rb_parent))
+		return -ENOMEM;
+	if ((vma->vm_flags & VM_ACCOUNT) &&
+	     security_vm_enough_memory_mm(mm, vma_pages(vma)))
+		return -ENOMEM;
+
 	/*
 	 * The vm_pgoff of a purely anonymous vma should be irrelevant
 	 * until its first write fault, when page's anon_vma and index
@@ -2894,12 +2901,6 @@ int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
 		BUG_ON(vma->anon_vma);
 		vma->vm_pgoff = vma->vm_start>> PAGE_SHIFT;
 	}
-	if (find_vma_links(mm, vma->vm_start, vma->vm_end,
-			   &prev, &rb_link, &rb_parent))
-		return -ENOMEM;
-	if ((vma->vm_flags & VM_ACCOUNT) &&
-	     security_vm_enough_memory_mm(mm, vma_pages(vma)))
-		return -ENOMEM;
 
 	vma_link(mm, vma, prev, rb_link, rb_parent);
 	return 0;
-- 
1.9.3

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