linux-ext4 - [patch 029/133] ext3: fix chain verification in ext3_get

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Message-Id: <200906172326.n5HNQNTI011090@imap1.linux-foundation.org>
Date:	Wed, 17 Jun 2009 16:26:23 -0700
From:	akpm@...ux-foundation.org
To:	torvalds@...ux-foundation.org
Cc:	akpm@...ux-foundation.org, jack@...e.cz, linux-ext4@...r.kernel.org
Subject: [patch 029/133] ext3: fix chain verification in ext3_get_blocks()

From: Jan Kara <jack@...e.cz>

Chain verification in ext3_get_blocks() has been hosed since it called
verify_chain(chain, NULL) which always returns success.  As a result
readers could in theory race with truncate.  On the other hand the race
probably cannot happen with the current locking scheme, since by the time
ext3_truncate() is called all the pages are already removed and hence
get_block() shouldn't be called on such pages...

Signed-off-by: Jan Kara <jack@...e.cz>
Cc: <linux-ext4@...r.kernel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
---

 fs/ext3/inode.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff -puN fs/ext3/inode.c~ext3-fix-chain-verification-in-ext3_get_blocks fs/ext3/inode.c
--- a/fs/ext3/inode.c~ext3-fix-chain-verification-in-ext3_get_blocks
+++ a/fs/ext3/inode.c
@@ -820,7 +820,7 @@ int ext3_get_blocks_handle(handle_t *han
 		while (count < maxblocks && count <= blocks_to_boundary) {
 			ext3_fsblk_t blk;
 
-			if (!verify_chain(chain, partial)) {
+			if (!verify_chain(chain, chain + depth - 1)) {
 				/*
 				 * Indirect block might be removed by
 				 * truncate while we were reading it.
_
--
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