From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 00277C433B4 for ; Mon, 19 Apr 2021 23:30:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D856D6102A for ; Mon, 19 Apr 2021 23:30:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232478AbhDSXay (ORCPT ); Mon, 19 Apr 2021 19:30:54 -0400 Received: from ozlabs.org ([203.11.71.1]:47525 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232468AbhDSXay (ORCPT ); Mon, 19 Apr 2021 19:30:54 -0400 Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 4FPNMx0wMRz9t8j; Tue, 20 Apr 2021 09:30:20 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ellerman.id.au; s=201909; t=1618875022; bh=sNnhdGDN+HHjQNHV3Mru459Lq1hls+4e4amt67I2FYo=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=aTcnBG+A0UW1DJiLAGpfVGzS2UwtCuQxBZYZZPaw5RQ6LrEiBoaLW8eZfFbo4mviZ 3irw7rHlVV1zGselzeJL+y373FUNYlUjUILT8uHWcs13JNBL8a7FdmmbdgNWNF1K0u O74buVWf+PZtjss2lfXrlN+6mrQUm+IS59Jj+EptGT9kMxa8Sg6/MMz/3qbJLHoGPS E1H7aBo8fGc8MZJRLLxsAp0pU+5+1HP+gvDNLqFtrhOQGPkoWV9KMbmlOtH6jpy9wo mjM7dhVhI0e/mVkQX0CyEBDxbYzo/s29JqQBovpo8qoGUzMDWiK6ccaC1aYTQttdaN KHciV4J1aFxRw== From: Michael Ellerman To: Lakshmi Ramasubramanian , Daniel Axtens , robh@kernel.org, dan.carpenter@oracle.com Cc: devicetree@vger.kernel.org, linuxppc-dev , kbuild-all@lists.01.org, bauerman@linux.ibm.com, lkp@intel.com Subject: Re: [PATCH] powerpc: Initialize local variable fdt to NULL in elf64_load() In-Reply-To: <2817d674-d420-580f-a0c1-b842da915a80@linux.microsoft.com> References: <20210415191437.20212-1-nramas@linux.microsoft.com> <4edb1433-4d1e-5719-ec9c-fd232b7cf71f@linux.microsoft.com> <87eefag241.fsf@linkitivity.dja.id.au> <87tuo6eh0j.fsf@mpe.ellerman.id.au> <2817d674-d420-580f-a0c1-b842da915a80@linux.microsoft.com> Date: Tue, 20 Apr 2021 09:30:16 +1000 Message-ID: <87pmypdf93.fsf@mpe.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org Lakshmi Ramasubramanian writes: > On 4/16/21 2:05 AM, Michael Ellerman wrote: > >> Daniel Axtens writes: >>>> On 4/15/21 12:14 PM, Lakshmi Ramasubramanian wrote: >>>> >>>> Sorry - missed copying device-tree and powerpc mailing lists. >>>> >>>>> There are a few "goto out;" statements before the local variable "fdt" >>>>> is initialized through the call to of_kexec_alloc_and_setup_fdt() in >>>>> elf64_load(). This will result in an uninitialized "fdt" being passed >>>>> to kvfree() in this function if there is an error before the call to >>>>> of_kexec_alloc_and_setup_fdt(). >>>>> >>>>> Initialize the local variable "fdt" to NULL. >>>>> >>> I'm a huge fan of initialising local variables! But I'm struggling to >>> find the code path that will lead to an uninit fdt being returned... >>> >>> The out label reads in part: >>> >>> /* Make kimage_file_post_load_cleanup free the fdt buffer for us. */ >>> return ret ? ERR_PTR(ret) : fdt; >>> >>> As far as I can tell, any time we get a non-zero ret, we're going to >>> return an error pointer rather than the uninitialised value... > > As Dan pointed out, the new code is in linux-next. > > I have copied the new one below - the function doesn't return fdt, but > instead sets it in the arch specific field (please see the link to the > updated elf_64.c below). > > https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git/tree/arch/powerpc/kexec/elf_64.c?h=for-next > >>> >>> (btw, it does look like we might leak fdt if we have an error after we >>> successfully kmalloc it.) >>> >>> Am I missing something? Can you link to the report for the kernel test >>> robot or from Dan? > > /* > * Once FDT buffer has been successfully passed to > kexec_add_buffer(), > * the FDT buffer address is saved in image->arch.fdt. In that > case, > * the memory cannot be freed here in case of any other error. > */ > if (ret && !image->arch.fdt) > kvfree(fdt); > > return ret ? ERR_PTR(ret) : NULL; > > In case of an error, the memory allocated for fdt is freed unless it has > already been passed to kexec_add_buffer(). It feels like the root of the problem is that the kvfree of fdt is in the wrong place. It's only allocated later in the function, so the error path should reflect that. Something like the patch below. cheers diff --git a/arch/powerpc/kexec/elf_64.c b/arch/powerpc/kexec/elf_64.c index 5a569bb51349..02662e72c53d 100644 --- a/arch/powerpc/kexec/elf_64.c +++ b/arch/powerpc/kexec/elf_64.c @@ -114,7 +114,7 @@ static void *elf64_load(struct kimage *image, char *kernel_buf, ret = setup_new_fdt_ppc64(image, fdt, initrd_load_addr, initrd_len, cmdline); if (ret) - goto out; + goto out_free_fdt; fdt_pack(fdt); @@ -125,7 +125,7 @@ static void *elf64_load(struct kimage *image, char *kernel_buf, kbuf.mem = KEXEC_BUF_MEM_UNKNOWN; ret = kexec_add_buffer(&kbuf); if (ret) - goto out; + goto out_free_fdt; /* FDT will be freed in arch_kimage_file_post_load_cleanup */ image->arch.fdt = fdt; @@ -140,18 +140,14 @@ static void *elf64_load(struct kimage *image, char *kernel_buf, if (ret) pr_err("Error setting up the purgatory.\n"); + goto out; + +out_free_fdt: + kvfree(fdt); out: kfree(modified_cmdline); kexec_free_elf_info(&elf_info); - /* - * Once FDT buffer has been successfully passed to kexec_add_buffer(), - * the FDT buffer address is saved in image->arch.fdt. In that case, - * the memory cannot be freed here in case of any other error. - */ - if (ret && !image->arch.fdt) - kvfree(fdt); - return ret ? ERR_PTR(ret) : NULL; } From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: multipart/mixed; boundary="===============7602349390637522178==" MIME-Version: 1.0 From: Michael Ellerman To: kbuild-all@lists.01.org Subject: Re: [PATCH] powerpc: Initialize local variable fdt to NULL in elf64_load() Date: Tue, 20 Apr 2021 09:30:16 +1000 Message-ID: <87pmypdf93.fsf@mpe.ellerman.id.au> In-Reply-To: <2817d674-d420-580f-a0c1-b842da915a80@linux.microsoft.com> List-Id: --===============7602349390637522178== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Lakshmi Ramasubramanian writes: > On 4/16/21 2:05 AM, Michael Ellerman wrote: > >> Daniel Axtens writes: >>>> On 4/15/21 12:14 PM, Lakshmi Ramasubramanian wrote: >>>> >>>> Sorry - missed copying device-tree and powerpc mailing lists. >>>> >>>>> There are a few "goto out;" statements before the local variable "fdt" >>>>> is initialized through the call to of_kexec_alloc_and_setup_fdt() in >>>>> elf64_load(). This will result in an uninitialized "fdt" being passed >>>>> to kvfree() in this function if there is an error before the call to >>>>> of_kexec_alloc_and_setup_fdt(). >>>>> >>>>> Initialize the local variable "fdt" to NULL. >>>>> >>> I'm a huge fan of initialising local variables! But I'm struggling to >>> find the code path that will lead to an uninit fdt being returned... >>> >>> The out label reads in part: >>> >>> /* Make kimage_file_post_load_cleanup free the fdt buffer for us. */ >>> return ret ? ERR_PTR(ret) : fdt; >>> >>> As far as I can tell, any time we get a non-zero ret, we're going to >>> return an error pointer rather than the uninitialised value... > > As Dan pointed out, the new code is in linux-next. > > I have copied the new one below - the function doesn't return fdt, but = > instead sets it in the arch specific field (please see the link to the = > updated elf_64.c below). > > https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git/tree/arch/= powerpc/kexec/elf_64.c?h=3Dfor-next > >>> >>> (btw, it does look like we might leak fdt if we have an error after we >>> successfully kmalloc it.) >>> >>> Am I missing something? Can you link to the report for the kernel test >>> robot or from Dan? > > /* > * Once FDT buffer has been successfully passed to = > kexec_add_buffer(), > * the FDT buffer address is saved in image->arch.fdt. In that = > case, > * the memory cannot be freed here in case of any other error. > */ > if (ret && !image->arch.fdt) > kvfree(fdt); > > return ret ? ERR_PTR(ret) : NULL; > > In case of an error, the memory allocated for fdt is freed unless it has = > already been passed to kexec_add_buffer(). It feels like the root of the problem is that the kvfree of fdt is in the wrong place. It's only allocated later in the function, so the error path should reflect that. Something like the patch below. cheers diff --git a/arch/powerpc/kexec/elf_64.c b/arch/powerpc/kexec/elf_64.c index 5a569bb51349..02662e72c53d 100644 --- a/arch/powerpc/kexec/elf_64.c +++ b/arch/powerpc/kexec/elf_64.c @@ -114,7 +114,7 @@ static void *elf64_load(struct kimage *image, char *ker= nel_buf, ret =3D setup_new_fdt_ppc64(image, fdt, initrd_load_addr, initrd_len, cmdline); if (ret) - goto out; + goto out_free_fdt; = fdt_pack(fdt); = @@ -125,7 +125,7 @@ static void *elf64_load(struct kimage *image, char *ker= nel_buf, kbuf.mem =3D KEXEC_BUF_MEM_UNKNOWN; ret =3D kexec_add_buffer(&kbuf); if (ret) - goto out; + goto out_free_fdt; = /* FDT will be freed in arch_kimage_file_post_load_cleanup */ image->arch.fdt =3D fdt; @@ -140,18 +140,14 @@ static void *elf64_load(struct kimage *image, char *k= ernel_buf, if (ret) pr_err("Error setting up the purgatory.\n"); = + goto out; + +out_free_fdt: + kvfree(fdt); out: kfree(modified_cmdline); kexec_free_elf_info(&elf_info); = - /* - * Once FDT buffer has been successfully passed to kexec_add_buffer(), - * the FDT buffer address is saved in image->arch.fdt. In that case, - * the memory cannot be freed here in case of any other error. - */ - if (ret && !image->arch.fdt) - kvfree(fdt); - return ret ? ERR_PTR(ret) : NULL; } =20 --===============7602349390637522178==--