udf: Improve table length check to avoid possible overflow
commit 57b9655d01ef057a523e810d29c37ac09b80eead upstream.
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.
Reported-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/fs/udf/super.c b/fs/udf/super.c
index 8d86a87..e660ffd 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -1283,7 +1283,7 @@
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) {
+ if (table_len > sb->s_blocksize - sizeof(*lvd)) {
udf_err(sb, "error loading logical volume descriptor: "
"Partition table too long (%u > %lu)\n", table_len,
sb->s_blocksize - sizeof(*lvd));