linux-kernel - [PATCH] scsi: Let scsi_execute_cmd() mark args->sshdr as invalid

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Date:   Thu, 11 May 2023 14:34:32 +0200
From:   Juergen Gross <jgross@...e.com>
To:     linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org
Cc:     Juergen Gross <jgross@...e.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        stable@...r.kernel.org
Subject: [PATCH] scsi: Let scsi_execute_cmd() mark args->sshdr as invalid

Some callers of scsi_execute_cmd() (like e.g. sd_spinup_disk()) are
passing an uninitialized struct sshdr and don't look at the return
value of scsi_execute_cmd() before looking at the contents of that
struct.

This can result in false positives when looking for specific error
conditions.

In order to fix that let scsi_execute_cmd() zero sshdr->response_code,
resulting in scsi_sense_valid() returning false.

Cc: stable@...r.kernel.org
Fixes: 3949e2f04262 ("scsi: simplify scsi_execute_req_flags")
Signed-off-by: Juergen Gross <jgross@...e.com>
---
I'm not aware of any real error having happened due to this problem,
but I thought it should be fixed anyway.
I _think_ 3949e2f04262 was introducing the problem, but I'm not 100%
sure it is really the commit to be blamed.
---
 drivers/scsi/scsi_lib.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index b7c569a42aa4..923336620bff 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -209,11 +209,17 @@ int scsi_execute_cmd(struct scsi_device *sdev, const unsigned char *cmd,
 	struct scsi_cmnd *scmd;
 	int ret;
 
-	if (!args)
+	if (!args) {
 		args = &default_args;
-	else if (WARN_ON_ONCE(args->sense &&
-			      args->sense_len != SCSI_SENSE_BUFFERSIZE))
-		return -EINVAL;
+	} else {
+		/* Mark sense data to be invalid. */
+		if (args->sshdr)
+			args->sshdr->response_code = 0;
+
+		if (WARN_ON_ONCE(args->sense &&
+				 args->sense_len != SCSI_SENSE_BUFFERSIZE))
+			return -EINVAL;
+	}
 
 	req = scsi_alloc_request(sdev->request_queue, opf, args->req_flags);
 	if (IS_ERR(req))
-- 
2.35.3