From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B61F31A6810; Thu, 30 Apr 2026 09:41:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777542116; cv=none; b=psT/T+eWrH0GbMblr9pvp66/w7IEJ3L8yHrHNBkQl+uF6Wj7AJ93AD2elxkjMXW7arzp+lGjX6pcZHm2ct14AfpIjhvpjW+e427PLBDMQP9yxqio8Y4Fas4/hKseaUXRKmfOBti7OoSARlKqpIHDJZnhQa7dB7vgbpmraOSx9gY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777542116; c=relaxed/simple; bh=OyBu5tnNP4uLFUjReaE5JPX/B70f++bdmkd1kLWqPn0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=PArih+gQwn+1xChSJnXf2C4WulcnwsOZ66QAQNEtzFFomd0bJWasyWdlOJgqMIw+WkFUU4/X2P9R3hBFwCG6jx8bDE9Rm9+tX/+ePCa/g+NvqzLTdEdyPsTd7wDl1mLO2Hjc2XMxuUxV/RUCNy5qesDyvRM4/k1DbJ2UMsAYa5I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=s3s0sJkM; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="s3s0sJkM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 276A1C2BCC6; Thu, 30 Apr 2026 09:41:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777542116; bh=OyBu5tnNP4uLFUjReaE5JPX/B70f++bdmkd1kLWqPn0=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=s3s0sJkMQ3cRJ+QpbRVXFug+mQS/53IZbKzYG0wtujLyLzKgivKx7lNQr+JCfLowP M8kf15e8SHdyd37DIaUvFjIFQtIItxVyKwPgFVWh61wdqUuYtxhi1BUuucAEGKnOG/ byikVw2YmDvx363PzwgBLRr+nVtb4R94JATBE5//says1RdvpUObW9zHOItJK5nVnc RbSkw16ySQalxLs/jjcwKXNbzhfi0GmZ8JUHJ4F4KxtWMm5GvtCKhrAlIkDEfUYJuP 62eJo9jzX2sFYJL6BJ9H1jz2WrL3MjmY41CaUpQ2JN2d+qLiu6OdGTwBk+ZFl4PvW6 9HT/1hE/3C7Ew== Message-ID: Date: Thu, 30 Apr 2026 11:41:49 +0200 Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] powerpc/text-patching: Fix possible stringop-overread compilation error To: Xie Yuanbin , andriy.shevchenko@intel.com, maddy@linux.ibm.com, mpe@ellerman.id.au, npiggin@gmail.com, kees@kernel.org, andy@kernel.org Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, lilinjie8@huawei.com, liaohua4@huawei.com References: <5cfae419-427a-471b-8bbe-645f56442e2c@kernel.org> <20260430072913.62348-1-xieyuanbin1@huawei.com> Content-Language: fr-FR From: "Christophe Leroy (CS GROUP)" In-Reply-To: <20260430072913.62348-1-xieyuanbin1@huawei.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Le 30/04/2026 à 09:28, Xie Yuanbin a écrit : > Hi, Christophe Leroy! > > On Mon, 9 Feb 2026 14:41:51 +0100, Christophe Leroy (CS GROUP) wrote: >> On 09/02/2026 14:25, Xie Yuanbin wrote: >>> When CONFIG_PPC64_ELF_ABI_V1=y, it seems that the try of lookupinp >>> the original non-dot symbol is missing. >>> >>> What about this (Only the compilation test is performed): >>> ```c >>> static inline unsigned long __ppc_kallsyms_lookup_name(const char *name) >>> { >>> unsigned long addr = kallsyms_lookup_name(name); >>> >>> if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2) && addr) >>> addr = ppc_function_entry((void *)addr); >>> >>> return addr; >>> } >>> >>> #define ppc_kallsyms_lookup_name(x) ({ \ >>> unsigned long addr = 0; \ >>> if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V1)) \ >>> addr = __ppc_kallsyms_lookup_name("." x); \ >>> if (!addr) \ >>> addr = __ppc_kallsyms_lookup_name(x); \ >>> addr; \ >>> }) >>> ``` >> >> Good point. >> >> To avoid duplicating the string I'd suggest: >> >> static inline unsigned long __ppc_kallsyms_lookup_name(const char *name) >> { >> unsigned long addr = kallsyms_lookup_name(name); >> >> if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V1) && !addr) >> addr = kallsyms_lookup_name(name + 1); >> if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2) && addr) >> addr = ppc_function_entry((void *)addr); >> >> return addr; >> } >> >> #ifdef CONFIG_PPC64_ELF_ABI_V1 >> #define ppc_kallsyms_lookup_name(x) __ppc_kallsyms_lookup_name("." x); >> #else >> #define ppc_kallsyms_lookup_name(x) __ppc_kallsyms_lookup_name(x) >> #endif > > I would like to submit the modification as a new patch, and include you > as Co-developer. Do you agree? Add me as Suggested-by: instead. Thanks Christophe > > Full of the patch: > ```patch > From fbf07e5c1a97da7c8572435537f2b92213ede39d Mon Sep 17 00:00:00 2001 > From: Xie Yuanbin > Date: Thu, 30 Apr 2026 14:15:26 +0800 > Subject: [PATCH V2] powerpc/text-patching: simplify the implementation of ppc_kallsyms_lookup_name() > > ppc_kallsyms_lookup_name() is called only twice in the kernel code, and > the parameters are all constant strings. strnlen(name, KSYM_NAME_LEN) is > called inside ppc_kallsyms_lookup_name(), when the compiler detects that > KSYM_NAME_LEN is larger then the constant strings, > the following error will be triggered: > ```log > CC arch/powerpc/kernel/optprobes.o > In file included from ./arch/powerpc/include/asm/kprobes.h:24, > from ./include/linux/kprobes.h:31, > from arch/powerpc/kernel/optprobes.c:8: > In function ‘ppc_kallsyms_lookup_name’, > inlined from ‘arch_prepare_optimized_kprobe’ at arch/powerpc/kernel/optprobes.c:209:21: > ./arch/powerpc/include/asm/text-patching.h:232:13: error: ‘strnlen’ specified bound 512 exceeds source size 19 [-Werror=stringop-overread] > 232 | if (strnlen(name, KSYM_NAME_LEN) >= KSYM_NAME_LEN) > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ > In function ‘ppc_kallsyms_lookup_name’, > inlined from ‘arch_prepare_optimized_kprobe’ at arch/powerpc/kernel/optprobes.c:210:22: > ./arch/powerpc/include/asm/text-patching.h:232:13: error: ‘strnlen’ specified bound 512 exceeds source size 13 [-Werror=stringop-overread] > 232 | if (strnlen(name, KSYM_NAME_LEN) >= KSYM_NAME_LEN) > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ > cc1: all warnings being treated as errors > ``` > > The error can be reproduced in the following ways: > Use lastest linux-next source, change ppc_kallsyms_lookup_name() to > __always_inline, use default ppc64_defconfig, set CONFIG_EXPERT=y, > CONFIG_PPC64_BIG_ENDIAN_ELF_ABI_V2=n, CONFIG_CC_OPTIMIZE_FOR_SIZE=y, > and use gcc-14 or a later version for compilation. > > Since ppc_kallsyms_lookup_name() is called only twice in the kernel, > and the parameters are all constant strins, simplify the implementation > of ppc_kallsyms_lookup_name() and avoid calling strnlen(). > > Cc: Andy Shevchenko > Cc: Kees Cook > Co-developed-by: Christophe Leroy (CS GROUP) > Signed-off-by: Christophe Leroy (CS GROUP) > Signed-off-by: Xie Yuanbin > --- > v1->v2: https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2F20260205100517.292858-2-xieyuanbin1%40huawei.com&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7C525ecaba66ea4e3b15f208dea68a3fa1%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C639131309913493421%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=aaK9PO2mGdxM3vuJBVP0lcl6VKfqs3VKih5VPcG0IxI%3D&reserved=0 > - Not use strlen() > > arch/powerpc/include/asm/text-patching.h | 42 ++++++++---------------- > 1 file changed, 17 insertions(+), 33 deletions(-) > > diff --git a/arch/powerpc/include/asm/text-patching.h b/arch/powerpc/include/asm/text-patching.h > index e7f14720f630..2d3f698cb4f1 100644 > --- a/arch/powerpc/include/asm/text-patching.h > +++ b/arch/powerpc/include/asm/text-patching.h > @@ -221,39 +221,23 @@ static inline unsigned long ppc_global_function_entry(void *func) > * - For ABIv1, we lookup the dot variant. > * - For ABIv2, we return the local entry point. > */ > -static inline unsigned long ppc_kallsyms_lookup_name(const char *name) > -{ > - unsigned long addr; > -#ifdef CONFIG_PPC64_ELF_ABI_V1 > - /* check for dot variant */ > - char dot_name[1 + KSYM_NAME_LEN]; > - bool dot_appended = false; > - > - if (strnlen(name, KSYM_NAME_LEN) >= KSYM_NAME_LEN) > - return 0; > - > - if (name[0] != '.') { > - dot_name[0] = '.'; > - dot_name[1] = '\0'; > - strlcat(dot_name, name, sizeof(dot_name)); > - dot_appended = true; > - } else { > - dot_name[0] = '\0'; > - strlcat(dot_name, name, sizeof(dot_name)); > - } > - addr = kallsyms_lookup_name(dot_name); > - if (!addr && dot_appended) > - /* Let's try the original non-dot symbol lookup */ > - addr = kallsyms_lookup_name(name); > -#elif defined(CONFIG_PPC64_ELF_ABI_V2) > - addr = kallsyms_lookup_name(name); > - if (addr) > - addr = ppc_function_entry((void *)addr); > -#else > - addr = kallsyms_lookup_name(name); > -#endif > - return addr; > -} > +static inline unsigned long __ppc_kallsyms_lookup_name(const char *name) > +{ > + unsigned long addr = kallsyms_lookup_name(name); > + > + if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V1) && !addr) > + addr = kallsyms_lookup_name(name + 1); > + if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2) && addr) > + addr = ppc_function_entry((void *)addr); > + > + return addr; > +} > + > +#ifdef CONFIG_PPC64_ELF_ABI_V1 > +#define ppc_kallsyms_lookup_name(x) __ppc_kallsyms_lookup_name("." x) > +#else > +#define ppc_kallsyms_lookup_name(x) __ppc_kallsyms_lookup_name(x) > +#endif > > /* > * Some instruction encodings commonly used in dynamic ftracing