linux-kernel - [PATCH 2/3] HWPOISON, hugetlbfs: fix "bad pmd" warning in unmapping hwpoisoned hugepage

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

Date:	Wed,  5 Dec 2012 16:47:37 -0500
From:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Andi Kleen <andi.kleen@...el.com>
Cc:	Tony Luck <tony.luck@...el.com>,
	Wu Fengguang <fengguang.wu@...el.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Subject: [PATCH 2/3] HWPOISON, hugetlbfs: fix "bad pmd" warning in unmapping hwpoisoned hugepage

When a process which used a hwpoisoned hugepage tries to exit() or
munmap(), the kernel can print out "bad pmd" message because page
table walker in free_pgtables() encounters 'hwpoisoned entry' on pmd.

This is because currently we fail to clear the hwpoisoned entry in
__unmap_hugepage_range(), so this patch simply does it.

Signed-off-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
---
 mm/hugetlb.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git v3.7-rc8.orig/mm/hugetlb.c v3.7-rc8/mm/hugetlb.c
index e61a749..fe7c2a7 100644
--- v3.7-rc8.orig/mm/hugetlb.c
+++ v3.7-rc8/mm/hugetlb.c
@@ -2387,8 +2387,10 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
 		/*
 		 * HWPoisoned hugepage is already unmapped and dropped reference
 		 */
-		if (unlikely(is_hugetlb_entry_hwpoisoned(pte)))
+		if (unlikely(is_hugetlb_entry_hwpoisoned(pte))) {
+			pte_clear(mm, address, ptep);
 			continue;
+		}
 
 		page = pte_page(pte);
 		/*
-- 
1.7.11.7

--
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/