[PATCH][next] scsi: storvsc: Use struct_size() helper in storvsc_queuecommand()

From: "Gustavo A. R. Silva" <gustavoars@kernel.org>
To: "K. Y. Srinivasan" <kys@microsoft.com>,
	Haiyang Zhang <haiyangz@microsoft.com>,
	Stephen Hemminger <sthemmin@microsoft.com>,
	Wei Liu <wei.liu@kernel.org>, Dexuan Cui <decui@microsoft.com>,
	"James E.J. Bottomley" <jejb@linux.ibm.com>,
	"Martin K. Petersen" <martin.petersen@oracle.com>
Cc: linux-hyperv@vger.kernel.org, linux-scsi@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	"Gustavo A. R. Silva" <gustavoars@kernel.org>,
	linux-hardening@vger.kernel.org
Subject: [PATCH][next] scsi: storvsc: Use struct_size() helper in storvsc_queuecommand()
Date: Tue, 25 Jan 2022 13:42:13 -0600	[thread overview]
Message-ID: <20220125194213.GA74670@embeddedor> (raw)

Make use of the struct_size() helper instead of an open-coded version,
in order to avoid any potential type mistakes or integer overflows that,
in the worst scenario, could lead to heap overflows.

Also, address the following sparse warnings:
drivers/scsi/storvsc_drv.c:1843:39: warning: using sizeof on a flexible structure

Link: https://github.com/KSPP/linux/issues/174
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
 drivers/scsi/storvsc_drv.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index 9a0bba5a51a7..89c20dfc6609 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -1755,7 +1755,7 @@ static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd)
 	struct scatterlist *sgl;
 	struct vmscsi_request *vm_srb;
 	struct vmbus_packet_mpb_array  *payload;
-	u32 payload_sz;
+	size_t payload_sz;
 	u32 length;
 
 	if (vmstor_proto_version <= VMSTOR_PROTO_VERSION_WIN8) {
@@ -1839,8 +1839,8 @@ static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd)
 
 		if (hvpg_count > MAX_PAGE_BUFFER_COUNT) {
 
-			payload_sz = (hvpg_count * sizeof(u64) +
-				      sizeof(struct vmbus_packet_mpb_array));
+			payload_sz = struct_size(payload, range.pfn_array,
+						 hvpg_count);
 			payload = kzalloc(payload_sz, GFP_ATOMIC);
 			if (!payload)
 				return SCSI_MLQUEUE_DEVICE_BUSY;
-- 
2.27.0

