linux-kernel - [PATCH v2][next] scsi: smartpqi: Replace one-element array with flexible-array member

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Message-ID: <Y+KC+VJ5xdmMaMUc@work>
Date:   Tue, 7 Feb 2023 10:57:29 -0600
From:   "Gustavo A. R. Silva" <gustavoars@...nel.org>
To:     Don Brace <don.brace@...rochip.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>
Cc:     storagedev@...rochip.com, linux-scsi@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        linux-hardening@...r.kernel.org, Kees Cook <keescook@...omium.org>
Subject: [PATCH v2][next] scsi: smartpqi: Replace one-element array with
 flexible-array member

One-element arrays are deprecated, and we are replacing them with flexible
array members instead. So, replace one-element array with flexible-array
member in struct report_log_lun_list.

This helps with the ongoing efforts to tighten the FORTIFY_SOURCE routines
on memcpy().

Link: https://github.com/KSPP/linux/issues/79
Link: https://github.com/KSPP/linux/issues/204
Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
---
Changes in v2:
 In v1 we thought that the original code was allocating one too-many
 entries for the list. However, Don Brance commented that the allocation
 was actually intentional[1]. So, I added a code comment with his feedback.
 Link: https://lore.kernel.org/linux-hardening/16e6c434-44af-2efb-d4bc-a253e93e5590@embeddedor.com/  [1]

v1:
 Link: https://lore.kernel.org/linux-hardening/c80c0979933e0c05e80d95792ef167a28640a14b.1663816572.git.gustavoars@kernel.org/

 drivers/scsi/smartpqi/smartpqi.h      | 2 +-
 drivers/scsi/smartpqi/smartpqi_init.c | 4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/smartpqi/smartpqi.h b/drivers/scsi/smartpqi/smartpqi.h
index af27bb0f3133..228838eb3686 100644
--- a/drivers/scsi/smartpqi/smartpqi.h
+++ b/drivers/scsi/smartpqi/smartpqi.h
@@ -954,7 +954,7 @@ struct report_log_lun {
 
 struct report_log_lun_list {
 	struct report_lun_header header;
-	struct report_log_lun lun_entries[1];
+	struct report_log_lun lun_entries[];
 };
 
 struct report_phys_lun_8byte_wwid {
diff --git a/drivers/scsi/smartpqi/smartpqi_init.c b/drivers/scsi/smartpqi/smartpqi_init.c
index d0446d4d4465..af8f1a8e9f8f 100644
--- a/drivers/scsi/smartpqi/smartpqi_init.c
+++ b/drivers/scsi/smartpqi/smartpqi_init.c
@@ -1277,6 +1277,10 @@ static int pqi_get_device_lists(struct pqi_ctrl_info *ctrl_info,
 	logdev_data_length = sizeof(struct report_lun_header) +
 		logdev_list_length;
 
+	/*
+	 * Notice that we take on an extra list entry (struct report_log_lun)
+	 * that is all zeros for the controller itself.
+	 */
 	internal_logdev_list = kmalloc(logdev_data_length +
 		sizeof(struct report_log_lun), GFP_KERNEL);
 	if (!internal_logdev_list) {
-- 
2.34.1