linux-kernel - [PATCH v2 3/4] xen: teach KASAN about grant tables

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Message-ID: <20200117125834.14552-4-sergey.dyasli@citrix.com>
Date:   Fri, 17 Jan 2020 12:58:33 +0000
From:   Sergey Dyasli <sergey.dyasli@...rix.com>
To:     <xen-devel@...ts.xen.org>, <kasan-dev@...glegroups.com>,
        <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>
CC:     Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        "Stefano Stabellini" <sstabellini@...nel.org>,
        George Dunlap <george.dunlap@...rix.com>,
        Ross Lagerwall <ross.lagerwall@...rix.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Sergey Dyasli <sergey.dyasli@...rix.com>
Subject: [PATCH v2 3/4] xen: teach KASAN about grant tables

From: Ross Lagerwall <ross.lagerwall@...rix.com>

Otherwise it produces lots of false positives when a guest starts using
PV I/O devices.

Signed-off-by: Ross Lagerwall <ross.lagerwall@...rix.com>
Signed-off-by: Sergey Dyasli <sergey.dyasli@...rix.com>
---
v1 --> v2:
- no changes

RFC --> v1:
- Slightly clarified the commit message
---
 drivers/xen/grant-table.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index 7b36b51cdb9f..ce95f7232de6 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -1048,6 +1048,7 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
 			foreign = xen_page_foreign(pages[i]);
 			foreign->domid = map_ops[i].dom;
 			foreign->gref = map_ops[i].ref;
+			kasan_alloc_pages(pages[i], 0);
 			break;
 		}
 
@@ -1084,8 +1085,10 @@ int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
 	if (ret)
 		return ret;
 
-	for (i = 0; i < count; i++)
+	for (i = 0; i < count; i++) {
 		ClearPageForeign(pages[i]);
+		kasan_free_pages(pages[i], 0);
+	}
 
 	return clear_foreign_p2m_mapping(unmap_ops, kunmap_ops, pages, count);
 }
-- 
2.17.1