From 56db1991690f076c2a7e3b2a226629cd10901690 Mon Sep 17 00:00:00 2001 From: Steve Magnani Date: Sun, 28 Jul 2019 14:19:12 -0500 Subject: udf: prevent allocation beyond UDF partition The UDF bitmap allocation code assumes that a recorded Unallocated Space Bitmap is compliant with ECMA-167 4/13, which requires that pad bytes between the end of the bitmap and the end of a logical block are all zero. When a recorded bitmap does not comply with this requirement, for example one padded with FF to the block boundary instead of 00, the allocator may "allocate" blocks that are outside the UDF partition extent. This can result in UDF volume descriptors being overwritten by file data or by partition-level descriptors, and in extreme cases, even in scribbling on a subsequent disk partition. Add a check that the block selected by the allocator actually resides within the UDF partition extent. Signed-off-by: Steven J. Magnani Link: https://lore.kernel.org/r/1564341552-129750-1-git-send-email-steve@digidescorp.com Signed-off-by: Jan Kara --- fs/udf/balloc.c | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'fs/udf') diff --git a/fs/udf/balloc.c b/fs/udf/balloc.c index ec85aeaed54a..02f03fadb75b 100644 --- a/fs/udf/balloc.c +++ b/fs/udf/balloc.c @@ -325,6 +325,17 @@ got_block: newblock = bit + (block_group << (sb->s_blocksize_bits + 3)) - (sizeof(struct spaceBitmapDesc) << 3); + if (newblock >= sbi->s_partmaps[partition].s_partition_len) { + /* + * Ran off the end of the bitmap, and bits following are + * non-compliant (not all zero) + */ + udf_err(sb, "bitmap for partition %d corrupted (block %u marked" + " as free, partition length is %u)\n", partition, + newblock, sbi->s_partmaps[partition].s_partition_len); + goto error_return; + } + if (!udf_clear_bit(bit, bh->b_data)) { udf_debug("bit already cleared for block %d\n", bit); goto repeat; -- cgit