From db108b67d81397cdbaf3f91aeca6e5eb5f71de1d Mon Sep 17 00:00:00 2001
From: Jan Beulich <jbeulich@suse.com>
Date: Fri, 26 Mar 2021 16:28:57 +0100
Subject: [PATCH] xen-blkback: don't leak persistent grants from
xen_blkbk_map()
commit a846738f8c3788d846ed1f587270d2f2e3d32432 upstream.
The fix for XSA-365 zapped too many of the ->persistent_gnt[] entries.
Ones successfully obtained should not be overwritten, but instead left
for xen_blkbk_unmap_prepare() to pick up and put.
This is XSA-371.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: stable@vger.kernel.org
Reviewed-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Wei Liu <wl@xen.org>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/block/xen-blkback/blkback.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index a703f365b5b19..ec292aa62046a 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -937,7 +937,7 @@ static int xen_blkbk_map(struct xen_blkif_ring *ring,
out:
for (i = last_map; i < num; i++) {
/* Don't zap current batch's valid persistent grants. */
- if(i >= last_map + segs_to_map)
+ if(i >= map_until)
pages[i]->persistent_gnt = NULL;
pages[i]->handle = BLKBACK_INVALID_HANDLE;
}