diff options
| author | Michael Bommarito <michael.bommarito@gmail.com> | 2026-04-13 17:12:40 -0400 |
|---|---|---|
| committer | Jan Kara <jack@suse.cz> | 2026-04-22 17:14:48 +0200 |
| commit | 55d41b0a20128e86b9e960dd2e3f0a2d69a18df7 (patch) | |
| tree | b687dc269849fdd3f60c4ec478da746d13305836 | |
| parent | cc85e337278001c325afecfbc9a739a3b1b205f2 (diff) | |
udf: reject descriptors with oversized CRC length
udf_read_tagged() skips CRC verification when descCRCLength +
sizeof(struct tag) exceeds the block size. A crafted UDF image can
set descCRCLength to an oversized value to bypass CRC validation
entirely; the descriptor is then accepted based solely on the 8-bit
tag checksum, which is trivially recomputable.
Reject such descriptors instead of silently accepting them. A
legitimate single-block descriptor should never have a CRC length that
exceeds the block.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-4-6
Assisted-by: Codex:gpt-5-4
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
Link: https://patch.msgid.link/20260413211240.853662-1-michael.bommarito@gmail.com
Signed-off-by: Jan Kara <jack@suse.cz>
| -rw-r--r-- | fs/udf/misc.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/fs/udf/misc.c b/fs/udf/misc.c index 0788593b6a1d..6928e378fbbd 100644 --- a/fs/udf/misc.c +++ b/fs/udf/misc.c @@ -230,8 +230,12 @@ struct buffer_head *udf_read_tagged(struct super_block *sb, uint32_t block, } /* Verify the descriptor CRC */ - if (le16_to_cpu(tag_p->descCRCLength) + sizeof(struct tag) > sb->s_blocksize || - le16_to_cpu(tag_p->descCRC) == crc_itu_t(0, + if (le16_to_cpu(tag_p->descCRCLength) + sizeof(struct tag) > sb->s_blocksize) { + udf_err(sb, "block %u: CRC length %u exceeds block size\n", + block, le16_to_cpu(tag_p->descCRCLength)); + goto error_out; + } + if (le16_to_cpu(tag_p->descCRC) == crc_itu_t(0, bh->b_data + sizeof(struct tag), le16_to_cpu(tag_p->descCRCLength))) return bh; |