[RHEL5 PATCH 2/3][v3] udf: Improve table length check to avoid possible overflow

[Nikola Pajkovsky]

https://bugzilla.redhat.com/show_bug.cgi?id=843141

commit 57b9655d01ef057a523e810d29c37ac09b80eead
Author: Jan Kara 
Date:   Tue Jul 10 17:58:04 2012 +0200

udf: Improve table length check to avoid possible overflow

When a partition table length is corrupted to be close to 1 << 32, the
    check for its length may overflow on 32-bit systems and we will think
    the length is valid. Later on the kernel can crash trying to read beyond
    end of buffer. Fix the check to avoid possible overflow.

CC: [e-mail]
    Reported-by: Ben Hutchings 
    Signed-off-by: Jan Kara

Signed-off-by: Nikola Pajkovsky 
---
 fs/udf/super.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/udf/super.c b/fs/udf/super.c
index f4a1800..77d83fe 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -1036,7 +1036,7 @@ udf_load_logicalvol(struct super_block *sb, struct buffer_head * bh, kernel_lb_a
    lvd = (struct logicalVolDesc *)bh->b_data;

table_len = le32_to_cpu(lvd->mapTableLength);
-	if (sizeof(*lvd) + table_len > sb->s_blocksize) {
+	if (table_len > sb->s_blocksize - sizeof(*lvd)) {
    	udf_error(sb, __FUNCTION__,
    		  "error loading logical volume descriptor: "
    		  "Partition table too long (%u > %lu)\n", table_len,