linux-kernel - [PATCH] Revert "scsi: storvsc: Validate length of incoming packet in storvsc_on_channel

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Date:   Fri, 11 Dec 2020 14:14:04 +0100
From:   "Andrea Parri (Microsoft)" <parri.andrea@...il.com>
To:     linux-kernel@...r.kernel.org, linux-hyperv@...r.kernel.org
Cc:     "K . Y . Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
        Michael Kelley <mikelley@...rosoft.com>,
        "Andrea Parri (Microsoft)" <parri.andrea@...il.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        linux-scsi@...r.kernel.org
Subject: [PATCH] Revert "scsi: storvsc: Validate length of incoming packet in storvsc_on_channel_callback()"

This reverts commit 3b8c72d076c42bf27284cda7b2b2b522810686f8.

Dexuan reported a regression where StorVSC fails to probe a device (and
where, consequently, the VM may fail to boot).  The root-cause analysis
led to a long-standing race condition that is exposed by the validation
/commit in question.  Let's put the new validation aside until a proper
solution for that race condition is in place.

Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@...il.com>
Cc: Dexuan Cui <decui@...rosoft.com>
Cc: "James E.J. Bottomley" <jejb@...ux.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@...cle.com>
Cc: linux-scsi@...r.kernel.org
---
 drivers/scsi/storvsc_drv.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index 99c8ff81de746..ded00a89bfc4e 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -1246,11 +1246,6 @@ static void storvsc_on_channel_callback(void *context)
 		request = (struct storvsc_cmd_request *)
 			((unsigned long)desc->trans_id);
 
-		if (hv_pkt_datalen(desc) < sizeof(struct vstor_packet) - vmscsi_size_delta) {
-			dev_err(&device->device, "Invalid packet len\n");
-			continue;
-		}
-
 		if (request == &stor_device->init_request ||
 		    request == &stor_device->reset_request) {
 			memcpy(&request->vstor_packet, packet,
-- 
2.25.1