linux-kernel - [PATCH AUTOSEL 5.14 28/40] Xen/gntdev: don't ignore kernel unmapping error

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Message-Id: <20210928055524.172051-28-sashal@kernel.org>
Date:   Tue, 28 Sep 2021 01:55:12 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Jan Beulich <jbeulich@...e.com>, Juergen Gross <jgross@...e.com>,
        Sasha Levin <sashal@...nel.org>, boris.ostrovsky@...cle.com,
        xen-devel@...ts.xenproject.org
Subject: [PATCH AUTOSEL 5.14 28/40] Xen/gntdev: don't ignore kernel unmapping error

From: Jan Beulich <jbeulich@...e.com>

[ Upstream commit f28347cc66395e96712f5c2db0a302ee75bafce6 ]

While working on XSA-361 and its follow-ups, I failed to spot another
place where the kernel mapping part of an operation was not treated the
same as the user space part. Detect and propagate errors and add a 2nd
pr_debug().

Signed-off-by: Jan Beulich <jbeulich@...e.com>
Reviewed-by: Juergen Gross <jgross@...e.com>
Link: https://lore.kernel.org/r/c2513395-74dc-aea3-9192-fd265aa44e35@suse.com
Signed-off-by: Juergen Gross <jgross@...e.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/xen/gntdev.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index a3e7be96527d..23fd09a9bbaf 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -396,6 +396,14 @@ static int __unmap_grant_pages(struct gntdev_grant_map *map, int offset,
 			map->unmap_ops[offset+i].handle,
 			map->unmap_ops[offset+i].status);
 		map->unmap_ops[offset+i].handle = INVALID_GRANT_HANDLE;
+		if (use_ptemod) {
+			if (map->kunmap_ops[offset+i].status)
+				err = -EINVAL;
+			pr_debug("kunmap handle=%u st=%d\n",
+				 map->kunmap_ops[offset+i].handle,
+				 map->kunmap_ops[offset+i].status);
+			map->kunmap_ops[offset+i].handle = INVALID_GRANT_HANDLE;
+		}
 	}
 	return err;
 }
-- 
2.33.0