From patchwork Sun Sep 25 07:16:53 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anton Blanchard X-Patchwork-Id: 674547 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3shdjJ2NDWz9srZ for ; Sun, 25 Sep 2016 17:17:56 +1000 (AEST) Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 3shdjJ1RdXzDrTX for ; Sun, 25 Sep 2016 17:17:56 +1000 (AEST) X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Received: from ozlabs.org (ozlabs.org [103.22.144.67]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3shdh76XJKzDrPd for ; Sun, 25 Sep 2016 17:16:55 +1000 (AEST) Received: by ozlabs.org (Postfix, from userid 1010) id 3shdh7536Yz9t0P; Sun, 25 Sep 2016 17:16:55 +1000 (AEST) From: Anton Blanchard To: benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au Subject: [PATCH] powerpc/vdso64: Use double word compare on pointers Date: Sun, 25 Sep 2016 17:16:53 +1000 Message-Id: <1474787813-22587-1-git-send-email-anton@ozlabs.org> X-Mailer: git-send-email 2.7.4 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" From: Anton Blanchard __kernel_get_syscall_map and __kernel_clock_getres use cmpli to check if the passed in pointer is non zero. cmpli maps to a 32 bit compare on binutils, so we ignore the top 32 bits. A simple test case can be created by passing in a bogus pointer with the bottom 32 bits clear. Using a clk_id that is handled by the VDSO, then one that is handled by the kernel shows the problem: printf("%d\n", clock_getres(CLOCK_REALTIME, (void *)0x100000000)); printf("%d\n", clock_getres(CLOCK_BOOTTIME, (void *)0x100000000)); And we get: 0 -1 The bigger issue is if we pass a valid pointer with the bottom 32 bits clear, in this case we will return success but won't write any data to the pointer. I stumbled across this issue because the LLVM integrated assembler doesn't accept cmpli with 3 arguments. Fix this by converting them to cmpldi. Cc: stable@vger.kernel.org Signed-off-by: Anton Blanchard --- arch/powerpc/kernel/vdso64/datapage.S | 2 +- arch/powerpc/kernel/vdso64/gettimeofday.S | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/kernel/vdso64/datapage.S b/arch/powerpc/kernel/vdso64/datapage.S index 184a6ba..abf17fe 100644 --- a/arch/powerpc/kernel/vdso64/datapage.S +++ b/arch/powerpc/kernel/vdso64/datapage.S @@ -59,7 +59,7 @@ V_FUNCTION_BEGIN(__kernel_get_syscall_map) bl V_LOCAL_FUNC(__get_datapage) mtlr r12 addi r3,r3,CFG_SYSCALL_MAP64 - cmpli cr0,r4,0 + cmpldi cr0,r4,0 crclr cr0*4+so beqlr li r0,NR_syscalls diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S index a76b4af..3820213 100644 --- a/arch/powerpc/kernel/vdso64/gettimeofday.S +++ b/arch/powerpc/kernel/vdso64/gettimeofday.S @@ -145,7 +145,7 @@ V_FUNCTION_BEGIN(__kernel_clock_getres) bne cr0,99f li r3,0 - cmpli cr0,r4,0 + cmpldi cr0,r4,0 crclr cr0*4+so beqlr lis r5,CLOCK_REALTIME_RES@h