From 45422b704db392a6d79d07ee3e3670b11048bd53 Mon Sep 17 00:00:00 2001
From: John Pittman <jpittman@redhat.com>
Date: Mon, 11 Nov 2019 16:43:20 -0800
Subject: [PATCH] md/raid10: prevent access of uninitialized resync_pages
 offset
Git-commit: 45422b704db392a6d79d07ee3e3670b11048bd53
Patch-mainline: v5.5-rc1
References: bsc#1166003

Due to unneeded multiplication in the out_free_pages portion of
r10buf_pool_alloc(), when using a 3-copy raid10 layout, it is
possible to access a resync_pages offset that has not been
initialized.  This access translates into a crash of the system
within resync_free_pages() while passing a bad pointer to
put_page().  Remove the multiplication, preventing access to the
uninitialized area.

Fixes: f0250618361db ("md: raid10: don't use bio's vec table to manage resync pages")
Cc: stable@vger.kernel.org # 4.12+
Signed-off-by: John Pittman <jpittman@redhat.com>
Suggested-by: David Jeffery <djeffery@redhat.com>
Reviewed-by: Laurence Oberman <loberman@redhat.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Coly Li <colyli@suse.de>

---
 drivers/md/raid10.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 2eca0a81a8c9..ec136e44aef7 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -191,7 +191,7 @@ static void * r10buf_pool_alloc(gfp_t gfp_flags, void *data)
 
 out_free_pages:
 	while (--j >= 0)
-		resync_free_pages(&rps[j * 2]);
+		resync_free_pages(&rps[j]);
 
 	j = 0;
 out_free_bio:
-- 
2.25.0