linux-kernel - [PATCH v4 5.10/5.15] ata: libata-scsi: check cdb length for VARIABLE_LENGTH

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Date: Thu, 27 Jun 2024 00:13:58 +0300
From: Mikhail Ukhin <mish.uxin2012@...dex.ru>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jens Axboe <axboe@...nel.dk>
Cc: Mikhail Ukhin <mish.uxin2012@...dex.ru>,
	stable@...r.kernel.org,
	linux-ide@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Pavel Koshutin <koshutin.pavel@...dex.ru>,
	lvc-project@...uxtesting.org
Subject: [PATCH v4 5.10/5.15] ata: libata-scsi: check cdb length for VARIABLE_LENGTH_CMD commands

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.
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@...il.com>
Signed-off-by: Mikhail Ivanov <iwanov-23@...ru>
Signed-off-by: Mikhail Ukhin <mish.uxin2012@...dex.ru>
---
 v2: The new addresses were added and the text was updated.
 v3: Checking has been moved to the function ata_scsi_var_len_cdb_xlat at
 the request of Damien Le Moal.
 v4: Extra opcode check removed.
 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..38488bd813d1 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -3948,7 +3948,11 @@ static unsigned int ata_scsi_var_len_cdb_xlat(struct ata_queued_cmd *qc)
 	struct scsi_cmnd *scmd = qc->scsicmd;
 	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.
--
2.25.1