From: Theodore Ts'o <tytso@mit.edu>
Date: Sun, 24 Aug 2008 02:27:22 +0000 (-0400)
Subject: libblkid: Strengthen the JFS probe routine
X-Git-Tag: v1.41.1~54
X-Git-Url: https://git.whamcloud.com/?a=commitdiff_plain;h=b41fb002257d4b997560cd77676b78219be03c24;p=tools%2Fe2fsprogs.git

libblkid: Strengthen the JFS probe routine

Check to make sure a JFS filesystem is really correct by checking the
relationship between the following fields in the JFS superblock:
s_bsize, s_l2bsize, s_pbsize, s_l2pbsize, and s_l2bfactor.  Thanks to
Lesh Bogdanow for this suggestion.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---

diff --git a/lib/blkid/probe.c b/lib/blkid/probe.c
index 225116a..92052e1 100644
--- a/lib/blkid/probe.c
+++ b/lib/blkid/probe.c
@@ -780,6 +780,16 @@ static int probe_jfs(struct blkid_probe *probe,
 
 	js = (struct jfs_super_block *)buf;
 
+	if (blkid_le32(js->js_bsize) != (1 << blkid_le16(js->js_l2bsize)))
+		return 1;
+
+	if (blkid_le32(js->js_pbsize) != (1 << blkid_le16(js->js_l2pbsize)))
+		return 1;
+
+	if ((blkid_le16(js->js_l2bsize) - blkid_le16(js->js_l2pbsize)) !=
+	    blkid_le16(js->js_l2bfactor))
+		return 1;
+
 	if (strlen((char *) js->js_label))
 		label = (char *) js->js_label;
 	blkid_set_tag(probe->dev, "LABEL", label, sizeof(js->js_label));
diff --git a/lib/blkid/probe.h b/lib/blkid/probe.h
index ac3a083..993156d 100644
--- a/lib/blkid/probe.h
+++ b/lib/blkid/probe.h
@@ -181,10 +181,13 @@ struct jfs_super_block {
 	unsigned char	js_magic[4];
 	__u32		js_version;
 	__u64		js_size;
-	__u32		js_bsize;
-	__u32		js_dummy1;
-	__u32		js_pbsize;
-	__u32		js_dummy2[27];
+	__u32		js_bsize;	/* 4: aggregate block size in bytes */
+	__u16		js_l2bsize;	/* 2: log2 of s_bsize */
+	__u16		js_l2bfactor;	/* 2: log2(s_bsize/hardware block size) */
+	__u32		js_pbsize;	/* 4: hardware/LVM block size in bytes */
+	__u16		js_l2pbsize;	/* 2: log2 of s_pbsize */
+	__u16 		js_pad;		/* 2: padding necessary for alignment */
+	__u32		js_dummy2[26];
 	unsigned char	js_uuid[16];
 	unsigned char	js_label[16];
 	unsigned char	js_loguuid[16];