linux-kernel - Re: [RESEND][PATCH] dir_index: error out instead of BUG on corrupt hash dir limit

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Date:	Sun, 9 Sep 2007 14:19:33 +0100
From:	"Duane Griffin" <duaneg@...da.com>
To:	Eric Sandeen <sandeen@...hat.com>
Cc:	linux-kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	ext4 development <linux-ext4@...r.kernel.org>
Subject: Re: [RESEND][PATCH] dir_index: error out instead of BUG on corrupt
	hash dir limit

Hi Eric,

On Fri, Aug 31, 2007 at 09:48:43PM -0500, Eric Sandeen wrote:
> (resend, this one got lost?  Got an acked-by from Andreas
> last go-round)

Sorry I missed this first time around. I came up with a very similar
fix recently, following a gentoo bug report.  However there are a few
more asserts later that you aren't currently handling. Below is an
incremental patch on top of yours that converts them too. Note that one
of them is in an if (0) block and maybe should be left alone -- what do
you think?

I tested all the changed code paths, except the if (0) one, using a
utility that appropriately corrupts ext3 images. The source code is
attached to the gentoo bug report here:

http://bugs.gentoo.org/show_bug.cgi?id=183207

Signed-off-by: Duane Griffin <duaneg@...da.com>

Index: linux-2.6-git/fs/ext3/namei.c
===================================================================
--- linux-2.6-git.orig/fs/ext3/namei.c
+++ linux-2.6-git/fs/ext3/namei.c
@@ -393,7 +393,15 @@ dx_probe(struct dentry *dentry, struct i
 	while (1)
 	{
 		count = dx_get_count(entries);
-		assert (count && count <= dx_get_limit(entries));
+		if (!count || count > dx_get_limit(entries)) {
+			ext3_warning(dir->i_sb, __FUNCTION__,
+				     "Corrupt limit in dir inode %ld\n",
+				     dir->i_ino);
+			brelse(bh);
+			*err = ERR_BAD_DX_DIR;
+			goto fail2;
+		}
+
 		p = entries + 1;
 		q = entries + count - 1;
 		while (p <= q)
@@ -419,7 +427,11 @@ dx_probe(struct dentry *dentry, struct i
 					break;
 				}
 			}
-			assert (at == p - 1);
+			if (at != p - 1) {
+				brelse(bh);
+				*err = ERR_BAD_DX_DIR;
+				goto fail2;
+			}
 		}
 
 		at = p - 1;
@@ -431,8 +443,16 @@ dx_probe(struct dentry *dentry, struct i
 		if (!(bh = ext3_bread (NULL,dir, dx_get_block(at), 0, err)))
 			goto fail2;
 		at = entries = ((struct dx_node *) bh->b_data)->entries;
-		assert (dx_get_limit(entries) == dx_node_limit (dir));
+		if (dx_get_limit(entries) != dx_node_limit (dir)) {
+			ext3_warning(dir->i_sb, __FUNCTION__,
+				     "Corrupt limit in dir inode %ld\n",
+				     dir->i_ino);
+			brelse(bh);
+			*err = ERR_BAD_DX_DIR;
+			goto fail2;
+		}
 		frame++;
+		frame->bh = NULL;
 	}
 fail2:
 	while (frame >= frame_in) {
Index: linux-2.6-git/fs/ext4/namei.c
===================================================================
--- linux-2.6-git.orig/fs/ext4/namei.c
+++ linux-2.6-git/fs/ext4/namei.c
@@ -393,7 +393,15 @@ dx_probe(struct dentry *dentry, struct i
 	while (1)
 	{
 		count = dx_get_count(entries);
-		assert (count && count <= dx_get_limit(entries));
+		if (!count || count > dx_get_limit(entries)) {
+			ext3_warning(dir->i_sb, __FUNCTION__,
+				     "Corrupt limit in dir inode %ld\n",
+				     dir->i_ino);
+			brelse(bh);
+			*err = ERR_BAD_DX_DIR;
+			goto fail2;
+		}
+
 		p = entries + 1;
 		q = entries + count - 1;
 		while (p <= q)
@@ -419,7 +427,11 @@ dx_probe(struct dentry *dentry, struct i
 					break;
 				}
 			}
-			assert (at == p - 1);
+			if (at != p - 1) {
+				brelse(bh);
+				*err = ERR_BAD_DX_DIR;
+				goto fail2;
+			}
 		}
 
 		at = p - 1;
@@ -431,8 +443,16 @@ dx_probe(struct dentry *dentry, struct i
 		if (!(bh = ext4_bread (NULL,dir, dx_get_block(at), 0, err)))
 			goto fail2;
 		at = entries = ((struct dx_node *) bh->b_data)->entries;
-		assert (dx_get_limit(entries) == dx_node_limit (dir));
+		if (dx_get_limit(entries) != dx_node_limit (dir)) {
+			ext3_warning(dir->i_sb, __FUNCTION__,
+				     "Corrupt limit in dir inode %ld\n",
+				     dir->i_ino);
+			brelse(bh);
+			*err = ERR_BAD_DX_DIR;
+			goto fail2;
+		}
 		frame++;
+		frame->bh = NULL;
 	}
 fail2:
 	while (frame >= frame_in) {

-- 
"I never could learn to drink that blood and call it wine" - Bob Dylan
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