Patch-mainline: v5.12-rc1
Git-commit: 7c77474b2d22176d2bfb592ec74e0f2cb71352c9
References: XSA-362 CVE-2021-26931 bsc#1181753
From: Jan Beulich <jbeulich@suse.com>
Date: Mon, 15 Feb 2021 08:55:57 +0100
Subject: [PATCH 8/9] xen-scsiback: don't "handle" error by BUG()

In particular -ENOMEM may come back here, from set_foreign_p2m_mapping().
Don't make problems worse, the more that handling elsewhere (together
with map's status fields now indicating whether a mapping wasn't even
attempted, and hence has to be considered failed) doesn't require this
odd way of dealing with errors.

This is part of XSA-362.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: stable@vger.kernel.org
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
---
 drivers/xen/xen-scsiback.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/xen/xen-scsiback.c b/drivers/xen/xen-scsiback.c
index fd32c3459b66..6d5eaea3373b 100644
--- a/drivers/xen/xen-scsiback.c
+++ b/drivers/xen/xen-scsiback.c
@@ -422,12 +422,12 @@ static int scsiback_gnttab_data_map_batch(struct gnttab_map_grant_ref *map,
 		return 0;
 
 	err = gnttab_map_refs(map, NULL, pg, cnt);
-	BUG_ON(err);
 	for (i = 0; i < cnt; i++) {
 		if (unlikely(map[i].status != GNTST_okay)) {
 			pr_err("invalid buffer -- could not remap it\n");
 			map[i].handle = SCSIBACK_INVALID_HANDLE;
-			err = -ENOMEM;
+			if (!err)
+				err = -ENOMEM;
 		} else {
 			get_page(pg[i]);
 		}
-- 
2.26.2