linux-kernel - [PATCH 4/7] xen/mmu: BUG_ON when racing to swap middle leaf.

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]

Message-Id: <1294679859-30029-5-git-send-email-konrad.wilk@oracle.com>
Date:	Mon, 10 Jan 2011 12:17:36 -0500
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	linux-kernel@...r.kernel.org,
	Jeremy Fitzhardinge <jeremy@...p.org>, hpa@...or.com,
	Ian Campbell <Ian.Campbell@...rix.com>
Cc:	Konrad Rzeszutek Wilk <konrad@...nel.org>,
	xen-devel@...ts.xensource.com, Jan Beulich <JBeulich@...ell.com>,
	Stefano Stabellini <stefano.stabellini@...citrix.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Subject: [PATCH 4/7] xen/mmu: BUG_ON when racing to swap middle leaf.

The initial bootup code uses set_phys_to_machine quite a lot, and after
bootup it would be used by the balloon driver. The balloon driver does have
mutex lock so this should not be necessary - but just in case, add
a BUG_ON if we do hit this scenario.

[v2: Change from WARN to BUG_ON]
Reviewed-by: Ian Campbell <Ian.Campbell@...citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
---
 arch/x86/xen/mmu.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 6d5b49b..0cce0c2 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -613,7 +613,8 @@ bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
 
 		/* Swap over from MISSING to IDENTITY if needed. */
 		if (p2m_top[topidx][mididx] == p2m_missing) {
-			p2m_top[topidx][mididx] = p2m_identity;
+			BUG_ON(cmpxchg(&p2m_top[topidx][mididx], p2m_missing,
+				p2m_identity) != p2m_missing);
 			return true;
 		}
 	}
-- 
1.7.1

--
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/