linux-kernel - [PATCH 4.15 058/202] [Variant 2/Spectre-v2] arm64: cpufeature: __this_cpu_has

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: <20180215151716.313237101@linuxfoundation.org>
Date:   Thu, 15 Feb 2018 16:15:58 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Suzuki K Poulose <suzuki.poulose@....com>,
        Marc Zyngier <marc.zyngier@....com>,
        James Morse <james.morse@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>
Subject: [PATCH 4.15 058/202] [Variant 2/Spectre-v2] arm64: cpufeature: __this_cpu_has_cap() shouldnt stop early

4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: James Morse <james.morse@....com>


Commit edf298cfce47 upstream.

this_cpu_has_cap() tests caps->desc not caps->matches, so it stops
walking the list when it finds a 'silent' feature, instead of
walking to the end of the list.

Prior to v4.6's 644c2ae198412 ("arm64: cpufeature: Test 'matches' pointer
to find the end of the list") we always tested desc to find the end of
a capability list. This was changed for dubious things like PAN_NOT_UAO.
v4.7's e3661b128e53e ("arm64: Allow a capability to be checked on
single CPU") added this_cpu_has_cap() using the old desc style test.

CC: Suzuki K Poulose <suzuki.poulose@....com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@....com>
Acked-by: Marc Zyngier <marc.zyngier@....com>
Signed-off-by: James Morse <james.morse@....com>
Signed-off-by: Catalin Marinas <catalin.marinas@....com>
Signed-off-by: Will Deacon <will.deacon@....com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/arm64/kernel/cpufeature.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1173,9 +1173,8 @@ static bool __this_cpu_has_cap(const str
 	if (WARN_ON(preemptible()))
 		return false;
 
-	for (caps = cap_array; caps->desc; caps++)
+	for (caps = cap_array; caps->matches; caps++)
 		if (caps->capability == cap &&
-		    caps->matches &&
 		    caps->matches(caps, SCOPE_LOCAL_CPU))
 			return true;
 	return false;