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

Greg Kroah-Hartman
2012-11-02T17:11:54Z

From: Alex Elder <elder@inktank.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@realimage.com>
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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;