[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/mpage.c b/fs/mpage.c
index f1d2d02..e431cb3 100644
--- a/fs/mpage.c
+++ b/fs/mpage.c
@@ -184,7 +184,7 @@ do_mpage_readpage(struct bio *bio, struct page *page, unsigned nr_pages,
 	if (page_has_buffers(page))
 		goto confused;
 
-	block_in_file = page->index << (PAGE_CACHE_SHIFT - blkbits);
+	block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits);
 	last_block = (i_size_read(inode) + blocksize - 1) >> blkbits;
 
 	bh.b_page = page;
@@ -466,7 +466,7 @@ __mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block,
 	 * The page has no buffers: map it to disk
 	 */
 	BUG_ON(!PageUptodate(page));
-	block_in_file = page->index << (PAGE_CACHE_SHIFT - blkbits);
+	block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits);
 	last_block = (i_size - 1) >> blkbits;
 	map_bh.b_page = page;
 	for (page_block = 0; page_block < blocks_per_page; ) {