linux-kernel - [ 092/180] udf: Avoid run away loop when partition table length is corrupted

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Date:	Tue, 02 Oct 2012 00:53:29 +0200
From:	Willy Tarreau <w@....eu>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Jan Kara <jack@...e.cz>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Willy Tarreau <w@....eu>
Subject: [ 092/180] udf: Avoid run away loop when partition table length is corrupted

2.6.32-longterm review patch.  If anyone has any objections, please let me know.

------------------

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

commit adee11b2085bee90bd8f4f52123ffb07882d6256 upstream.

Check provided length of partition table so that (possibly maliciously)
corrupted partition table cannot cause accessing data beyond current buffer.

Signed-off-by: Jan Kara <jack@...e.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Willy Tarreau <w@....eu>
---
 fs/udf/super.c |   11 ++++++++++-
 1 files changed, 10 insertions(+), 1 deletions(-)

diff --git a/fs/udf/super.c b/fs/udf/super.c
index ee6b3af..0388d43 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -1249,6 +1249,7 @@ static int udf_load_logicalvol(struct super_block *sb, sector_t block,
 	struct genericPartitionMap *gpm;
 	uint16_t ident;
 	struct buffer_head *bh;
+	unsigned int table_len;
 	int ret = 0;
 
 	bh = udf_read_tagged(sb, block, block, &ident);
@@ -1257,6 +1258,14 @@ static int udf_load_logicalvol(struct super_block *sb, sector_t block,
 	BUG_ON(ident != TAG_IDENT_LVD);
 	lvd = (struct logicalVolDesc *)bh->b_data;
 
+	table_len = le32_to_cpu(lvd->mapTableLength);
+	if (sizeof(*lvd) + table_len > sb->s_blocksize) {
+		udf_error(sb, __func__, "error loading logical volume descriptor: "
+		          "Partition table too long (%u > %lu)\n", table_len,
+		          sb->s_blocksize - sizeof(*lvd));
+		goto out_bh;
+	}
+
 	i = udf_sb_alloc_partition_maps(sb, le32_to_cpu(lvd->numPartitionMaps));
 	if (i != 0) {
 		ret = i;
@@ -1264,7 +1273,7 @@ static int udf_load_logicalvol(struct super_block *sb, sector_t block,
 	}
 
 	for (i = 0, offset = 0;
-	     i < sbi->s_partitions && offset < le32_to_cpu(lvd->mapTableLength);
+	     i < sbi->s_partitions && offset < table_len;
 	     i++, offset += gpm->partitionMapLength) {
 		struct udf_part_map *map = &sbi->s_partmaps[i];
 		gpm = (struct genericPartitionMap *)
-- 
1.7.2.1.45.g54fbc



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