linux-kernel - [PATCH 2/2] bfs: check that filesystem fits on the blockdevice

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Date:	Tue, 21 Oct 2008 12:51:42 +0200
From:	Eric Sesterhenn <snakebyte@....de>
To:	akpm@...ux-foundation.org
Cc:	tigran@...azian.fsnet.co.uk, linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] bfs: check that filesystem fits on the blockdevice

Since all sanity checks rely on the validity of s_start which gets only
checked to be smaller than s_end, we should also check if s_end is sane.
Now we also try to retrieve the last block of the filesystem, which is
computed by s_end. If this fails, something is bogus.

Signed-off-by: Eric Sesterhenn <snakebyte@....de>
Acked-by: Tigran Aivazian <tigran@...azian.fsnet.co.uk>


--- linux/fs/bfs/inode.c.1	2008-09-17 16:00:06.000000000 +0200
+++ linux/fs/bfs/inode.c	2008-09-17 16:17:54.000000000 +0200
@@ -390,6 +390,18 @@ static int bfs_fill_super(struct super_b
 			- le32_to_cpu(bfs_sb->s_start)) >> BFS_BSIZE_BITS;
 	info->si_freei = 0;
 	info->si_lf_eblk = 0;
+
+	/* can we read the last block? */
+	bh = sb_bread(s, info->si_blocks - 1);
+	if (!bh) {
+		printf("Last block not available: %lu\n", info->si_blocks - 1);
+		iput(inode);
+		ret = -EIO;
+		kfree(info->si_imap);
+		goto out;
+	}
+	brelse(bh);
+
 	bh = NULL;
 	for (i = BFS_ROOT_INO; i <= info->si_lasti; i++) {
 		struct bfs_inode *di;
--
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