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From: Mikhail Ukhin <mish.uxin2012@yandex.ru>
To: Jens Axboe <axboe@kernel.dk>
Cc: Mikhail Ukhin <mish.uxin2012@yandex.ru>,
	linux-ide@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Damien Le Moal <damien.lemoal@opensource.wdc.com>,
	Niklas Cassel <cassel@kernel.org>,
	Pavel Koshutin <koshutin.pavel@yandex.ru>,
	Artem Sadovnikov <ancowi69@gmail.com>,
	Mikhail Ivanov <iwanov-23@bk.ru>
Subject: [PATCH 5.10/5.15] ata: libata-scsi: check cdb length for VARIABLE_LENGTH_CMD commands
Date: Thu, 28 Mar 2024 18:00:26 +0300
Message-Id: <20240328150026.9129-1-mish.uxin2012@yandex.ru>
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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").
Backporting this commit would require significant changes to the code so
it is bettter to use a simple fix for that particular error.

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>
---
 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 dfa090ccd21c..77589e911d3d 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -4065,6 +4065,9 @@ int __ata_scsi_queuecmd(struct scsi_cmnd *scmd, struct ata_device *dev)
 
 	if (unlikely(!scmd->cmd_len))
 		goto bad_cdb_len;
+
+	if (scsi_op == VARIABLE_LENGTH_CMD && scmd->cmd_len < 32)
+		goto bad_cdb_len;
 
 	if (dev->class == ATA_DEV_ATA || dev->class == ATA_DEV_ZAC) {
 		if (unlikely(scmd->cmd_len > dev->cdb_len))
-- 
2.25.1