fix #5448: support SCSI contollers with bad VDP page length encoding again

The reporter has an Adaptec 5805 controller (using the aacraid
driver), which reports a byteswapped page length for VPD page 0. It
reports "02 00" as page length instead of "00 02".

This stopped working with kernel 6.8.4 due to commit b5fc07a5fb56
("scsi: core: Consult supported VPD page list prior to fetching page")

To address that issue limit the page search scope to the size of our
VPD buffer to guard against devices returning a larger page count than
requested.

Reported-by: Peter Schneider <pschneider1968@googlemail.com>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

patches/kernel/0015-scsi-core-Handle-devices-which-return-an-unusually-l.patch

@@ -0,0 +1,49 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: "Martin K. Petersen" <martin.petersen@oracle.com>
+Date: Mon, 20 May 2024 22:30:40 -0400
+Subject: [PATCH] scsi: core: Handle devices which return an unusually large
+ VPD page count
+
+Peter Schneider reported that a system would no longer boot after
+updating to 6.8.4.  Peter bisected the issue and identified commit
+b5fc07a5fb56 ("scsi: core: Consult supported VPD page list prior to
+fetching page") as being the culprit.
+
+Turns out the enclosure device in Peter's system reports a byteswapped
+page length for VPD page 0. It reports "02 00" as page length instead
+of "00 02". This causes us to attempt to access 516 bytes (page length
++ header) of information despite only 2 pages being present.
+
+Limit the page search scope to the size of our VPD buffer to guard
+against devices returning a larger page count than requested.
+
+Link: https://lore.kernel.org/r/20240521023040.2703884-1-martin.petersen@oracle.com
+Fixes: b5fc07a5fb56 ("scsi: core: Consult supported VPD page list prior to fetching page")
+Cc: stable@vger.kernel.org
+Reported-by: Peter Schneider <pschneider1968@googlemail.com>
+Closes: https://lore.kernel.org/all/eec6ebbf-061b-4a7b-96dc-ea748aa4d035@googlemail.com/
+Tested-by: Peter Schneider <pschneider1968@googlemail.com>
+Reviewed-by: Bart Van Assche <bvanassche@acm.org>
+Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
+---
+ drivers/scsi/scsi.c | 7 +++++++
+ 1 file changed, 7 insertions(+)
+
+diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
+index 8cad9792a562..b3ff3a633a1e 100644
+--- a/drivers/scsi/scsi.c
++++ b/drivers/scsi/scsi.c
+@@ -350,6 +350,13 @@ static int scsi_get_vpd_size(struct scsi_device *sdev, u8 page)
+ 		if (result < SCSI_VPD_HEADER_SIZE)
+ 			return 0;
+ 
++		if (result > sizeof(vpd)) {
++			dev_warn_once(&sdev->sdev_gendev,
++				      "%s: long VPD page 0 length: %d bytes\n",
++				      __func__, result);
++			result = sizeof(vpd);
++		}
++
+ 		result -= SCSI_VPD_HEADER_SIZE;
+ 		if (!memchr(&vpd[SCSI_VPD_HEADER_SIZE], page, result))
+ 			return 0;