From caf1e3a932f926c54b6325291542ec5d705dd2c8 Mon Sep 17 00:00:00 2001
From: Andrew Morton <akpm@linux-foundation.org>
Date: Fri, 7 Jun 2013 10:07:51 +1000
Subject: [PATCH] vmcore-support-mmap-on-proc-vmcore-fix

use min(), switch to conventional error-unwinding approach

Cc: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Lisa Mitchell <lisa.mitchell@hp.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 fs/proc/vmcore.c | 27 ++++++++++-----------------
 1 file changed, 10 insertions(+), 17 deletions(-)

diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index 423796979640..0f6db5269d38 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -218,9 +218,7 @@ static int mmap_vmcore(struct file *file, struct vm_area_struct *vma)
 	if (start < elfcorebuf_sz) {
 		u64 pfn;
 
-		tsz = elfcorebuf_sz - start;
-		if (size < tsz)
-			tsz = size;
+		tsz = min(elfcorebuf_sz - (size_t)start, size);
 		pfn = __pa(elfcorebuf + start) >> PAGE_SHIFT;
 		if (remap_pfn_range(vma, vma->vm_start, pfn, tsz,
 				    vma->vm_page_prot))
@@ -236,15 +234,11 @@ static int mmap_vmcore(struct file *file, struct vm_area_struct *vma)
 	if (start < elfcorebuf_sz + elfnotes_sz) {
 		void *kaddr;
 
-		tsz = elfcorebuf_sz + elfnotes_sz - start;
-		if (size < tsz)
-			tsz = size;
+		tsz = min(elfcorebuf_sz + elfnotes_sz - (size_t)start, size);
 		kaddr = elfnotes_buf + start - elfcorebuf_sz;
 		if (remap_vmalloc_range_partial(vma, vma->vm_start + len,
-						kaddr, tsz)) {
-			do_munmap(vma->vm_mm, vma->vm_start, len);
-			return -EAGAIN;
-		}
+						kaddr, tsz))
+			goto fail;
 		size -= tsz;
 		start += tsz;
 		len += tsz;
@@ -257,16 +251,12 @@ static int mmap_vmcore(struct file *file, struct vm_area_struct *vma)
 		if (start < m->offset + m->size) {
 			u64 paddr = 0;
 
-			tsz = m->offset + m->size - start;
-			if (size < tsz)
-				tsz = size;
+			tsz = min_t(size_t, m->offset + m->size - start, size);
 			paddr = m->paddr + start - m->offset;
 			if (remap_pfn_range(vma, vma->vm_start + len,
 					    paddr >> PAGE_SHIFT, tsz,
-					    vma->vm_page_prot)) {
-				do_munmap(vma->vm_mm, vma->vm_start, len);
-				return -EAGAIN;
-			}
+					    vma->vm_page_prot))
+				goto fail;
 			size -= tsz;
 			start += tsz;
 			len += tsz;
@@ -277,6 +267,9 @@ static int mmap_vmcore(struct file *file, struct vm_area_struct *vma)
 	}
 
 	return 0;
+fail:
+	do_munmap(vma->vm_mm, vma->vm_start, len);
+	return -EAGAIN;
 }
 
 static const struct file_operations proc_vmcore_operations = {
-- 
2.39.5