linux-kernel - [PATCH 1/3] Xen/gntdev: don't ignore kernel unmapping error

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Date:   Sun, 30 Oct 2022 03:12:41 -0400
From:   Demi Marie Obenour <demi@...isiblethingslab.com>
To:     Juergen Gross <jgross@...e.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Sasha Levin <sashal@...nel.org>,
        Marek Marczykowski-Górecki 
        <marmarek@...isiblethingslab.com>
Cc:     Jan Beulich <jbeulich@...e.com>, xen-devel@...ts.xenproject.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Demi Marie Obenour <demi@...isiblethingslab.com>
Subject: [PATCH 1/3] Xen/gntdev: don't ignore kernel unmapping error

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

commit f28347cc66395e96712f5c2db0a302ee75bafce6 upstream.

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: Demi Marie Obenour <demi@...isiblethingslab.com>
Co-authored-by: Demi Marie Obenour <demi@...isiblethingslab.com>
---
 drivers/xen/gntdev.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 54fee4087bf1078803c230ad2081aafa8415cf53..8cf9f2074c5d57bff81364d7d6a70b0007a85e44 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -407,6 +407,14 @@ static void __unmap_grant_pages_done(int result,
 			map->unmap_ops[offset+i].handle,
 			map->unmap_ops[offset+i].status);
 		map->unmap_ops[offset+i].handle = -1;
+		if (use_ptemod) {
+			WARN_ON(map->kunmap_ops[offset+i].status &&
+				map->kunmap_ops[offset+i].handle != -1);
+			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 = -1;
+		}
 	}
 	/*
 	 * Decrease the live-grant counter.  This must happen after the loop to
-- 
2.38.1