[PATCH v5 5.10/5.15] ata: libata-scsi: check cdb length for VARIABLE_LENGTH_CMD commands

[Artem Sadovnikov <ancowi69@gmail.com>]

Fuzzing of 5.10 stable branch reports a slab-out-of-bounds error in
ata_scsi_pass_thru.

The error is fixed in 5.18 by commit ce70fd9a551a ("scsi: core: Remove the
cmd field from struct scsi_request") upstream.

The problem is that the length of the received SCSI command is not
validated if scsi_op == VARIABLE_LENGTH_CMD. It can lead to out-of-bounds
reading if the user sends a request with SCSI command of length less than
32.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Signed-off-by: Artem Sadovnikov <ancowi69@gmail.com>
Signed-off-by: Mikhail Ivanov <iwanov-23@bk.ru>
Signed-off-by: Mikhail Ukhin <mish.uxin2012@yandex.ru>
---
 drivers/ata/libata-scsi.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 36f32fa052df..4397986db053 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -3949,6 +3949,9 @@ static unsigned int ata_scsi_var_len_cdb_xlat(struct ata_queued_cmd *qc)
 	const u8 *cdb = scmd->cmnd;
 	const u16 sa = get_unaligned_be16(&cdb[8]);
 
+	if (scmd->cmd_len != 32)
+		return 1;
+
 	/*
 	 * if service action represents a ata pass-thru(32) command,
 	 * then pass it to ata_scsi_pass_thru handler.
-- 
2.34.1