From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935208AbeE1XIq (ORCPT ); Mon, 28 May 2018 19:08:46 -0400 Received: from gate.crashing.org ([63.228.1.57]:42765 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751432AbeE1XIm (ORCPT ); Mon, 28 May 2018 19:08:42 -0400 Message-ID: <0f79b2e8bd86d95f0acd087432f0efef0abc86d3.camel@kernel.crashing.org> Subject: Re: [PATCH] powerpc/64: Fix build failure with GCC 8.1 From: Benjamin Herrenschmidt To: Christophe Leroy , Paul Mackerras , Michael Ellerman Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Date: Tue, 29 May 2018 09:08:17 +1000 In-Reply-To: <1d3fd6a6c35e41d3e25ebe5256adf021369ada7c.1527525305.git.christophe.leroy@c-s.fr> References: <1d3fd6a6c35e41d3e25ebe5256adf021369ada7c.1527525305.git.christophe.leroy@c-s.fr> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.1 (3.28.1-2.fc28) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2018-05-28 at 16:37 +0000, Christophe Leroy wrote: > CC arch/powerpc/kernel/nvram_64.o > arch/powerpc/kernel/nvram_64.c: In function 'nvram_create_partition': > arch/powerpc/kernel/nvram_64.c:1042:2: error: 'strncpy' specified bound 12 equals destination size [-Werror=stringop-truncation] > strncpy(new_part->header.name, name, 12); > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > CC arch/powerpc/kernel/trace/ftrace.o > In function 'make_field', > inlined from 'ps3_repository_read_boot_dat_address' at arch/powerpc/platforms/ps3/repository.c:900:9: > arch/powerpc/platforms/ps3/repository.c:106:2: error: 'strncpy' output truncated before terminating nul copying 8 bytes from a string of the same length [-Werror=stringop-truncation] > strncpy((char *)&n, text, 8); > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ That's not completely correct, here it's gcc warning being over- zealous. The old specs I could find define the format to be a 12 characters strings *or* a less-than-12 characters NUL terminated string. So it's perfectly ok to drop the trailing 0 if the name happens to be exactly 12 characters. Cheers, Ben. > Signed-off-by: Christophe Leroy > --- > arch/powerpc/kernel/nvram_64.c | 2 +- > arch/powerpc/platforms/ps3/repository.c | 4 ++-- > 2 files changed, 3 insertions(+), 3 deletions(-) > > diff --git a/arch/powerpc/kernel/nvram_64.c b/arch/powerpc/kernel/nvram_64.c > index ba681dac7b46..7507448cd904 100644 > --- a/arch/powerpc/kernel/nvram_64.c > +++ b/arch/powerpc/kernel/nvram_64.c > @@ -1039,7 +1039,7 @@ loff_t __init nvram_create_partition(const char *name, int sig, > new_part->index = free_part->index; > new_part->header.signature = sig; > new_part->header.length = size; > - strncpy(new_part->header.name, name, 12); > + strncpy(new_part->header.name, name, sizeof(new_part->header.name) - 1); > new_part->header.checksum = nvram_checksum(&new_part->header); > > rc = nvram_write_header(new_part); > diff --git a/arch/powerpc/platforms/ps3/repository.c b/arch/powerpc/platforms/ps3/repository.c > index 50dbaf24b1ee..b4d6628eec5e 100644 > --- a/arch/powerpc/platforms/ps3/repository.c > +++ b/arch/powerpc/platforms/ps3/repository.c > @@ -101,9 +101,9 @@ static u64 make_first_field(const char *text, u64 index) > > static u64 make_field(const char *text, u64 index) > { > - u64 n; > + u64 n = 0; > > - strncpy((char *)&n, text, 8); > + memcpy((char *)&n, text, min(sizeof(n), strlen(text))); > return n + index; > } >