linux-kernel - [ 14/24] ceph: avoid 32-bit page index overflow

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Date:	Fri,  2 Nov 2012 10:07:02 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	alan@...rguk.ukuu.org.uk,
	Mohamed Pakkeer <pakkeer.mohideen@...limage.com>,
	Alex Elder <elder@...tank.com>, Sage Weil <sage@...tank.com>
Subject: [ 14/24] ceph: avoid 32-bit page index overflow

3.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Alex Elder <elder@...tank.com>

commit 6285bc231277419255f3498d3eb5ddc9f8e7fe79 upstream.

A pgoff_t is defined (by default) to have type (unsigned long).  On
architectures such as i686 that's a 32-bit type.  The ceph address
space code was attempting to produce 64 bit offsets by shifting a
page's index by PAGE_CACHE_SHIFT, but the result was not what was
desired because the shift occurred before the result got promoted
to 64 bits.

Fix this by converting all uses of page->index used in this way to
use the page_offset() macro, which ensures the 64-bit result has the
intended value.

This fixes http://tracker.newdream.net/issues/3112

Reported-by:  Mohamed Pakkeer <pakkeer.mohideen@...limage.com>
Signed-off-by: Alex Elder <elder@...tank.com>
Reviewed-by: Sage Weil <sage@...tank.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/ceph/addr.c |   11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -205,7 +205,7 @@ static int readpage_nounlock(struct file
 	dout("readpage inode %p file %p page %p index %lu\n",
 	     inode, filp, page, page->index);
 	err = ceph_osdc_readpages(osdc, ceph_vino(inode), &ci->i_layout,
-				  page->index << PAGE_CACHE_SHIFT, &len,
+				  (u64) page_offset(page), &len,
 				  ci->i_truncate_seq, ci->i_truncate_size,
 				  &page, 1, 0);
 	if (err == -ENOENT)
@@ -286,7 +286,7 @@ static int start_read(struct inode *inod
 	int nr_pages = 0;
 	int ret;
 
-	off = page->index << PAGE_CACHE_SHIFT;
+	off = (u64) page_offset(page);
 
 	/* count pages */
 	next_index = page->index;
@@ -426,7 +426,7 @@ static int writepage_nounlock(struct pag
 	struct ceph_inode_info *ci;
 	struct ceph_fs_client *fsc;
 	struct ceph_osd_client *osdc;
-	loff_t page_off = page->index << PAGE_CACHE_SHIFT;
+	loff_t page_off = page_offset(page);
 	int len = PAGE_CACHE_SIZE;
 	loff_t i_size;
 	int err = 0;
@@ -817,8 +817,7 @@ get_more_pages:
 			/* ok */
 			if (locked_pages == 0) {
 				/* prepare async write request */
-				offset = (unsigned long long)page->index
-					<< PAGE_CACHE_SHIFT;
+				offset = (u64) page_offset(page);
 				len = wsize;
 				req = ceph_osdc_new_request(&fsc->client->osdc,
 					    &ci->i_layout,
@@ -1180,7 +1179,7 @@ static int ceph_page_mkwrite(struct vm_a
 	struct inode *inode = vma->vm_file->f_dentry->d_inode;
 	struct page *page = vmf->page;
 	struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
-	loff_t off = page->index << PAGE_CACHE_SHIFT;
+	loff_t off = page_offset(page);
 	loff_t size, len;
 	int ret;
 


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