linux-kernel - [PATCH RESEND -mm 1/2] mm: add !pte_present() check on existing hugetlb

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:	Tue, 18 Mar 2014 22:29:38 -0400
From:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Sasha Levin <sasha.levin@...cle.com>,
	Rik van Riel <riel@...hat.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH RESEND -mm 1/2] mm: add !pte_present() check on existing hugetlb_entry callbacks

Page table walker doesn't check non-present hugetlb entry in common path,
so hugetlb_entry() callbacks must check it. The reason for this behavior
is that some callers want to handle it in its own way.

However, some callers don't check it now, which causes unpredictable result,
for example when we have a race between migrating hugepage and reading
/proc/pid/numa_maps. This patch fixes it by adding !pte_present checks on
buggy callbacks.

This bug exists for years and got visible by introducing hugepage migration.

ChangeLog v2:
- fix if condition (check !pte_present() instead of pte_present())

Reported-by: Sasha Levin <sasha.levin@...cle.com>
Signed-off-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Cc: stable@...r.kernel.org # 3.12+
---
 fs/proc/task_mmu.c | 3 +++
 mm/mempolicy.c     | 6 +++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git v3.14-rc7-mmotm-2014-03-18-16-37.orig/fs/proc/task_mmu.c v3.14-rc7-mmotm-2014-03-18-16-37/fs/proc/task_mmu.c
index d9d9d4f41544..f75ce811d430 100644
--- v3.14-rc7-mmotm-2014-03-18-16-37.orig/fs/proc/task_mmu.c
+++ v3.14-rc7-mmotm-2014-03-18-16-37/fs/proc/task_mmu.c
@@ -1300,6 +1300,9 @@ static int gather_hugetlb_stats(pte_t *pte, unsigned long addr,
 	if (pte_none(*pte))
 		return 0;
 
+	if (!pte_present(*pte))
+		return 0;
+
 	page = pte_page(*pte);
 	if (!page)
 		return 0;
diff --git v3.14-rc7-mmotm-2014-03-18-16-37.orig/mm/mempolicy.c v3.14-rc7-mmotm-2014-03-18-16-37/mm/mempolicy.c
index af635c458dee..9d2ef4111a4c 100644
--- v3.14-rc7-mmotm-2014-03-18-16-37.orig/mm/mempolicy.c
+++ v3.14-rc7-mmotm-2014-03-18-16-37/mm/mempolicy.c
@@ -524,8 +524,12 @@ static int queue_pages_hugetlb(pte_t *pte, unsigned long addr,
 	unsigned long flags = qp->flags;
 	int nid;
 	struct page *page;
+	pte_t entry;
 
-	page = pte_page(huge_ptep_get(pte));
+	entry = huge_ptep_get(pte);
+	if (!pte_present(entry))
+		return 0;
+	page = pte_page(entry);
 	nid = page_to_nid(page);
 	if (node_isset(nid, *qp->nmask) == !!(flags & MPOL_MF_INVERT))
 		return 0;
-- 
1.8.5.3

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/