linux-kernel - [PATCH v2] mm/page_isolation: fix potential missing call to unset_migratetype

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 13 Sep 2021 19:51:25 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <akpm@...ux-foundation.org>
CC:     <david@...hat.com>, <mhocko@...e.com>, <vbabka@...e.cz>,
        <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        <linmiaohe@...wei.com>
Subject: [PATCH v2] mm/page_isolation: fix potential missing call to unset_migratetype_isolate()

In start_isolate_page_range() undo path, pfn_to_online_page() just checks
the first pfn in a pageblock while __first_valid_page() will traverse the
pageblock until the first online pfn is found. So we may miss the call to
unset_migratetype_isolate() in undo path and pages will remain isolated
unexpectedly. Fix this by calling undo_isolate_page_range() and this will
also help to simplify the code further.

Fixes: 2ce13640b3f4 ("mm: __first_valid_page skip over offline pages")
Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
Cc: <stable@...r.kernel.org>
---
v1->v2:
  Simplify the code further per David Hildenbrand.
---
 mm/page_isolation.c | 20 +++-----------------
 1 file changed, 3 insertions(+), 17 deletions(-)

diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index a95c2c6562d0..f93cc63d8fa1 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -183,7 +183,6 @@ int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 			     unsigned migratetype, int flags)
 {
 	unsigned long pfn;
-	unsigned long undo_pfn;
 	struct page *page;
 
 	BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages));
@@ -193,25 +192,12 @@ int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 	     pfn < end_pfn;
 	     pfn += pageblock_nr_pages) {
 		page = __first_valid_page(pfn, pageblock_nr_pages);
-		if (page) {
-			if (set_migratetype_isolate(page, migratetype, flags)) {
-				undo_pfn = pfn;
-				goto undo;
-			}
+		if (page && set_migratetype_isolate(page, migratetype, flags)) {
+			undo_isolate_page_range(start_pfn, pfn, migratetype);
+			return -EBUSY;
 		}
 	}
 	return 0;
-undo:
-	for (pfn = start_pfn;
-	     pfn < undo_pfn;
-	     pfn += pageblock_nr_pages) {
-		struct page *page = pfn_to_online_page(pfn);
-		if (!page)
-			continue;
-		unset_migratetype_isolate(page, migratetype);
-	}
-
-	return -EBUSY;
 }
 
 /*
-- 
2.23.0