linux-kernel - [PATCH] scsi: megaraid_sas: struct MR_HOST_DEVICE_LIST: Replace 1-element array with flexible array

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Message-Id: <20240711155841.work.839-kees@kernel.org>
Date: Thu, 11 Jul 2024 08:58:42 -0700
From: Kees Cook <kees@...nel.org>
To: Kashyap Desai <kashyap.desai@...adcom.com>
Cc: Kees Cook <kees@...nel.org>,
	Sumit Saxena <sumit.saxena@...adcom.com>,
	Shivasharan S <shivasharan.srikanteshwara@...adcom.com>,
	Chandrakanth patil <chandrakanth.patil@...adcom.com>,
	"James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
	"Martin K. Petersen" <martin.petersen@...cle.com>,
	megaraidlinux.pdl@...adcom.com,
	linux-scsi@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-hardening@...r.kernel.org
Subject: [PATCH] scsi: megaraid_sas: struct MR_HOST_DEVICE_LIST: Replace 1-element array with flexible array

Replace the deprecated[1] use of a 1-element array in
struct MR_HOST_DEVICE_LIST with a modern flexible array.

One binary difference appears in megasas_host_device_list_query():

        struct MR_HOST_DEVICE_LIST *ci;
	...
        ci = instance->host_device_list_buf;
	...
        memset(ci, 0, sizeof(*ci));

The memset() clears only the non-flexible array fields. Looking at the
rest of the function, this appears to be fine: firmware is using this
region to communicate with the kernel, so it likely never made sense to
clear the first MR_HOST_DEVICE_LIST_ENTRY.

Link: https://github.com/KSPP/linux/issues/79 [1]
Signed-off-by: Kees Cook <kees@...nel.org>
---
Cc: Kashyap Desai <kashyap.desai@...adcom.com>
Cc: Sumit Saxena <sumit.saxena@...adcom.com>
Cc: Shivasharan S <shivasharan.srikanteshwara@...adcom.com>
Cc: Chandrakanth patil <chandrakanth.patil@...adcom.com>
Cc: "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>
Cc: "Martin K. Petersen" <martin.petersen@...cle.com>
Cc: megaraidlinux.pdl@...adcom.com
Cc: linux-scsi@...r.kernel.org
---
 drivers/scsi/megaraid/megaraid_sas.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/megaraid/megaraid_sas.h b/drivers/scsi/megaraid/megaraid_sas.h
index 84cf77c48c0d..088cc40ae866 100644
--- a/drivers/scsi/megaraid/megaraid_sas.h
+++ b/drivers/scsi/megaraid/megaraid_sas.h
@@ -814,12 +814,12 @@ struct MR_HOST_DEVICE_LIST {
 	__le32			size;
 	__le32			count;
 	__le32			reserved[2];
-	struct MR_HOST_DEVICE_LIST_ENTRY	host_device_list[1];
+	struct MR_HOST_DEVICE_LIST_ENTRY	host_device_list[] __counted_by_le(count);
 } __packed;
 
 #define HOST_DEVICE_LIST_SZ (sizeof(struct MR_HOST_DEVICE_LIST) +	       \
 			      (sizeof(struct MR_HOST_DEVICE_LIST_ENTRY) *      \
-			      (MEGASAS_MAX_PD + MAX_LOGICAL_DRIVES_EXT - 1)))
+			      (MEGASAS_MAX_PD + MAX_LOGICAL_DRIVES_EXT)))
 
 
 /*
-- 
2.34.1