[PATCH] fix possible PAGE_CACHE_SHIFT overflows

We've had two instances recently of overflows when doing

	64_bit_value = (32_bit_value << PAGE_CACHE_SHIFT)

I did a tree-wide grep of `<<.*PAGE_CACHE_SHIFT' and this is the result.

- afs_rxfs_fetch_descriptor.offset is of type off_t, which seems broken.

- jfs and jffs are limited to 4GB anyway.

- reiserfs map_block_for_writepage() takes an unsigned long for the block -
  it should take sector_t.  (It'll fail for huge filesystems with
  blocksize<PAGE_CACHE_SIZE)

- cramfs_read() needs to use sector_t (I think cramsfs is busted on large
  filesystems anyway)

- affs is limited in file size anyway.

- I generally didn't fix 32-bit overflows in directory operations.

- arm's __flush_dcache_page() is peculiar.  What if the page lies beyond 4G?

- gss_wrap_req_priv() needs checking (snd_buf->page_base)

Cc: Oleg Drokin <green@linuxhacker.ru>
Cc: David Howells <dhowells@redhat.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: <reiserfs-dev@namesys.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Anton Altaparmakov <aia21@cantab.net>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: <linux-fsdevel@vger.kernel.org>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/jffs/inode-v23.c b/fs/jffs/inode-v23.c
index 3dcc6d2162cb..2559ee10beda 100644
--- a/fs/jffs/inode-v23.c
+++ b/fs/jffs/inode-v23.c
@@ -757,7 +757,7 @@ jffs_do_readpage_nolock(struct file *file, struct page *page)
 
 	read_len = 0;
 	result = 0;
-	offset = page->index << PAGE_CACHE_SHIFT;
+	offset = page_offset(page);
 
 	kmap(page);
 	buf = page_address(page);
@@ -1545,7 +1545,7 @@ jffs_commit_write(struct file *filp, struct page *page,
 {
        void *addr = page_address(page) + from;
        /* XXX: PAGE_CACHE_SHIFT or PAGE_SHIFT */
-       loff_t pos = (page->index<<PAGE_CACHE_SHIFT) + from;
+       loff_t pos = page_offset(page) + from;
 
        return jffs_file_write(filp, addr, to-from, &pos);
 } /* jffs_commit_write() */