From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Eric W. Biederman" Subject: Re: [PATCH v2 18/18] uaccess: drop maining CONFIG_SET_FS users Date: Thu, 17 Feb 2022 16:36:20 -0600 Message-ID: <8735khi0ij.fsf@email.froward.int.ebiederm.org> References: <20220216131332.1489939-1-arnd@kernel.org> <20220216131332.1489939-19-arnd@kernel.org> Mime-Version: 1.0 Return-path: In-Reply-To: <20220216131332.1489939-19-arnd@kernel.org> (Arnd Bergmann's message of "Wed, 16 Feb 2022 14:13:32 +0100") List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Arnd Bergmann Cc: Linus Torvalds , Christoph Hellwig , linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-api@vger.kernel.org, arnd@arndb.de, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk, linux@armlinux.org.uk, will@kernel.org, guoren@kernel.org, bcain@codeaurora.org, geert@linux-m68k.org, monstr@monstr.eu, tsbogend@alpha.franken.de, nickhu@andestech.com, green.hu@gmail.com, dinguyen@kernel.org, shorne@gmail.com, deller@gmx.de, mpe@ellerman.id.au, peterz@infradead.org, mingo@redhat.com, mark.rutland@arm.com, hca@linux.ibm.com, dalias@libc.org, davem@davemloft.net, richard@nod.at, x86@kernel.org, jcmvbkbc@gmail.com, akpm@linux-foundation.org, ardb@kernel.org, linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-csky@vger.kernel. Arnd Bergmann writes: > From: Arnd Bergmann > > There are no remaining callers of set_fs(), so CONFIG_SET_FS > can be removed globally, along with the thread_info field and > any references to it. > > This turns access_ok() into a cheaper check against TASK_SIZE_MAX. > > With CONFIG_SET_FS gone, so drop all remaining references to > set_fs()/get_fs(), mm_segment_t and uaccess_kernel(). For the bits I have looked at recently, and think I understand. Acked-by: "Eric W. Biederman" > > Signed-off-by: Arnd Bergmann > --- > fs/exec.c | 6 -- > kernel/exit.c | 14 ----- > kernel/kthread.c | 5 -- > > diff --git a/fs/exec.c b/fs/exec.c > index 79f2c9483302..bc68a0c089ac 100644 > --- a/fs/exec.c > +++ b/fs/exec.c > @@ -1303,12 +1303,6 @@ int begin_new_exec(struct linux_binprm * bprm) > if (retval) > goto out_unlock; > > - /* > - * Ensure that the uaccess routines can actually operate on userspace > - * pointers: > - */ > - force_uaccess_begin(); > - > if (me->flags & PF_KTHREAD) > free_kthread_struct(me); > me->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD | > diff --git a/kernel/exit.c b/kernel/exit.c > index b00a25bb4ab9..0884a75bc2f8 100644 > --- a/kernel/exit.c > +++ b/kernel/exit.c > @@ -737,20 +737,6 @@ void __noreturn do_exit(long code) > > WARN_ON(blk_needs_flush_plug(tsk)); > > - /* > - * If do_dead is called because this processes oopsed, it's possible > - * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before > - * continuing. Amongst other possible reasons, this is to prevent > - * mm_release()->clear_child_tid() from writing to a user-controlled > - * kernel address. > - * > - * On uptodate architectures force_uaccess_begin is a noop. On > - * architectures that still have set_fs/get_fs in addition to handling > - * oopses handles kernel threads that run as set_fs(KERNEL_DS) by > - * default. > - */ > - force_uaccess_begin(); > - > kcov_task_exit(tsk); > > coredump_task_exit(tsk); > diff --git a/kernel/kthread.c b/kernel/kthread.c > index 38c6dd822da8..16c2275d4b50 100644 > --- a/kernel/kthread.c > +++ b/kernel/kthread.c > @@ -55,7 +55,6 @@ struct kthread { > int result; > int (*threadfn)(void *); > void *data; > - mm_segment_t oldfs; > struct completion parked; > struct completion exited; > #ifdef CONFIG_BLK_CGROUP > @@ -1441,8 +1440,6 @@ void kthread_use_mm(struct mm_struct *mm) > mmdrop(active_mm); > else > smp_mb(); > - > - to_kthread(tsk)->oldfs = force_uaccess_begin(); > } > EXPORT_SYMBOL_GPL(kthread_use_mm); > > @@ -1457,8 +1454,6 @@ void kthread_unuse_mm(struct mm_struct *mm) > WARN_ON_ONCE(!(tsk->flags & PF_KTHREAD)); > WARN_ON_ONCE(!tsk->mm); > > - force_uaccess_end(to_kthread(tsk)->oldfs); > - > task_lock(tsk); > /* > * When a kthread stops operating on an address space, the loop 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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1DE91C433F5 for ; Thu, 17 Feb 2022 22:37:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240110AbiBQWhT (ORCPT ); Thu, 17 Feb 2022 17:37:19 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:54534 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232023AbiBQWhS (ORCPT ); Thu, 17 Feb 2022 17:37:18 -0500 Received: from out01.mta.xmission.com (out01.mta.xmission.com [166.70.13.231]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 341D7811B9; Thu, 17 Feb 2022 14:36:55 -0800 (PST) Received: from in02.mta.xmission.com ([166.70.13.52]:48942) by out01.mta.xmission.com with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1nKpOJ-001bK3-23; Thu, 17 Feb 2022 15:36:47 -0700 Received: from ip68-227-174-4.om.om.cox.net ([68.227.174.4]:32906 helo=email.froward.int.ebiederm.org.xmission.com) by in02.mta.xmission.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1nKpOG-00GKIm-Md; Thu, 17 Feb 2022 15:36:46 -0700 From: "Eric W. Biederman" To: Arnd Bergmann Cc: Linus Torvalds , Christoph Hellwig , linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-api@vger.kernel.org, arnd@arndb.de, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk, linux@armlinux.org.uk, will@kernel.org, guoren@kernel.org, bcain@codeaurora.org, geert@linux-m68k.org, monstr@monstr.eu, tsbogend@alpha.franken.de, nickhu@andestech.com, green.hu@gmail.com, dinguyen@kernel.org, shorne@gmail.com, deller@gmx.de, mpe@ellerman.id.au, peterz@infradead.org, mingo@redhat.com, mark.rutland@arm.com, hca@linux.ibm.com, dalias@libc.org, davem@davemloft.net, richard@nod.at, x86@kernel.org, jcmvbkbc@gmail.com, akpm@linux-foundation.org, ardb@kernel.org, linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org References: <20220216131332.1489939-1-arnd@kernel.org> <20220216131332.1489939-19-arnd@kernel.org> Date: Thu, 17 Feb 2022 16:36:20 -0600 In-Reply-To: <20220216131332.1489939-19-arnd@kernel.org> (Arnd Bergmann's message of "Wed, 16 Feb 2022 14:13:32 +0100") Message-ID: <8735khi0ij.fsf@email.froward.int.ebiederm.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1nKpOG-00GKIm-Md;;;mid=<8735khi0ij.fsf@email.froward.int.ebiederm.org>;;;hst=in02.mta.xmission.com;;;ip=68.227.174.4;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1/V+0C7NWKuSkdwXmdluwhE5ZIu3hq7L5I= X-SA-Exim-Connect-IP: 68.227.174.4 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: Re: [PATCH v2 18/18] uaccess: drop maining CONFIG_SET_FS users X-SA-Exim-Version: 4.2.1 (built Sat, 08 Feb 2020 21:53:50 +0000) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org Arnd Bergmann writes: > From: Arnd Bergmann > > There are no remaining callers of set_fs(), so CONFIG_SET_FS > can be removed globally, along with the thread_info field and > any references to it. > > This turns access_ok() into a cheaper check against TASK_SIZE_MAX. > > With CONFIG_SET_FS gone, so drop all remaining references to > set_fs()/get_fs(), mm_segment_t and uaccess_kernel(). For the bits I have looked at recently, and think I understand. Acked-by: "Eric W. Biederman" > > Signed-off-by: Arnd Bergmann > --- > fs/exec.c | 6 -- > kernel/exit.c | 14 ----- > kernel/kthread.c | 5 -- > > diff --git a/fs/exec.c b/fs/exec.c > index 79f2c9483302..bc68a0c089ac 100644 > --- a/fs/exec.c > +++ b/fs/exec.c > @@ -1303,12 +1303,6 @@ int begin_new_exec(struct linux_binprm * bprm) > if (retval) > goto out_unlock; > > - /* > - * Ensure that the uaccess routines can actually operate on userspace > - * pointers: > - */ > - force_uaccess_begin(); > - > if (me->flags & PF_KTHREAD) > free_kthread_struct(me); > me->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD | > diff --git a/kernel/exit.c b/kernel/exit.c > index b00a25bb4ab9..0884a75bc2f8 100644 > --- a/kernel/exit.c > +++ b/kernel/exit.c > @@ -737,20 +737,6 @@ void __noreturn do_exit(long code) > > WARN_ON(blk_needs_flush_plug(tsk)); > > - /* > - * If do_dead is called because this processes oopsed, it's possible > - * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before > - * continuing. Amongst other possible reasons, this is to prevent > - * mm_release()->clear_child_tid() from writing to a user-controlled > - * kernel address. > - * > - * On uptodate architectures force_uaccess_begin is a noop. On > - * architectures that still have set_fs/get_fs in addition to handling > - * oopses handles kernel threads that run as set_fs(KERNEL_DS) by > - * default. > - */ > - force_uaccess_begin(); > - > kcov_task_exit(tsk); > > coredump_task_exit(tsk); > diff --git a/kernel/kthread.c b/kernel/kthread.c > index 38c6dd822da8..16c2275d4b50 100644 > --- a/kernel/kthread.c > +++ b/kernel/kthread.c > @@ -55,7 +55,6 @@ struct kthread { > int result; > int (*threadfn)(void *); > void *data; > - mm_segment_t oldfs; > struct completion parked; > struct completion exited; > #ifdef CONFIG_BLK_CGROUP > @@ -1441,8 +1440,6 @@ void kthread_use_mm(struct mm_struct *mm) > mmdrop(active_mm); > else > smp_mb(); > - > - to_kthread(tsk)->oldfs = force_uaccess_begin(); > } > EXPORT_SYMBOL_GPL(kthread_use_mm); > > @@ -1457,8 +1454,6 @@ void kthread_unuse_mm(struct mm_struct *mm) > WARN_ON_ONCE(!(tsk->flags & PF_KTHREAD)); > WARN_ON_ONCE(!tsk->mm); > > - force_uaccess_end(to_kthread(tsk)->oldfs); > - > task_lock(tsk); > /* > * When a kthread stops operating on an address space, the loop From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Eric W. Biederman" Date: Thu, 17 Feb 2022 22:36:20 +0000 Subject: Re: [PATCH v2 18/18] uaccess: drop maining CONFIG_SET_FS users Message-Id: <8735khi0ij.fsf@email.froward.int.ebiederm.org> List-Id: References: <20220216131332.1489939-1-arnd@kernel.org> <20220216131332.1489939-19-arnd@kernel.org> In-Reply-To: <20220216131332.1489939-19-arnd@kernel.org> (Arnd Bergmann's message of "Wed, 16 Feb 2022 14:13:32 +0100") MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Arnd Bergmann Cc: Linus Torvalds , Christoph Hellwig , linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-api@vger.kernel.org, arnd@arndb.de, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk, linux@armlinux.org.uk, will@kernel.org, guoren@kernel.org, bcain@codeaurora.org, geert@linux-m68k.org, monstr@monstr.eu, tsbogend@alpha.franken.de, nickhu@andestech.com, green.hu@gmail.com, dinguyen@kernel.org, shorne@gmail.com, deller@gmx.de, mpe@ellerman.id.au, peterz@infradead.org, mingo@redhat.com, mark.rutland@arm.com, hca@linux.ibm.com, dalias@libc.org, davem@davemloft.net, richard@nod.at, x86@kernel.org, jcmvbkbc@gmail.com, akpm@linux-foundation.org, ardb@kernel.org, linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org Arnd Bergmann writes: > From: Arnd Bergmann > > There are no remaining callers of set_fs(), so CONFIG_SET_FS > can be removed globally, along with the thread_info field and > any references to it. > > This turns access_ok() into a cheaper check against TASK_SIZE_MAX. > > With CONFIG_SET_FS gone, so drop all remaining references to > set_fs()/get_fs(), mm_segment_t and uaccess_kernel(). For the bits I have looked at recently, and think I understand. Acked-by: "Eric W. Biederman" > > Signed-off-by: Arnd Bergmann > --- > fs/exec.c | 6 -- > kernel/exit.c | 14 ----- > kernel/kthread.c | 5 -- > > diff --git a/fs/exec.c b/fs/exec.c > index 79f2c9483302..bc68a0c089ac 100644 > --- a/fs/exec.c > +++ b/fs/exec.c > @@ -1303,12 +1303,6 @@ int begin_new_exec(struct linux_binprm * bprm) > if (retval) > goto out_unlock; > > - /* > - * Ensure that the uaccess routines can actually operate on userspace > - * pointers: > - */ > - force_uaccess_begin(); > - > if (me->flags & PF_KTHREAD) > free_kthread_struct(me); > me->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD | > diff --git a/kernel/exit.c b/kernel/exit.c > index b00a25bb4ab9..0884a75bc2f8 100644 > --- a/kernel/exit.c > +++ b/kernel/exit.c > @@ -737,20 +737,6 @@ void __noreturn do_exit(long code) > > WARN_ON(blk_needs_flush_plug(tsk)); > > - /* > - * If do_dead is called because this processes oopsed, it's possible > - * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before > - * continuing. Amongst other possible reasons, this is to prevent > - * mm_release()->clear_child_tid() from writing to a user-controlled > - * kernel address. > - * > - * On uptodate architectures force_uaccess_begin is a noop. On > - * architectures that still have set_fs/get_fs in addition to handling > - * oopses handles kernel threads that run as set_fs(KERNEL_DS) by > - * default. > - */ > - force_uaccess_begin(); > - > kcov_task_exit(tsk); > > coredump_task_exit(tsk); > diff --git a/kernel/kthread.c b/kernel/kthread.c > index 38c6dd822da8..16c2275d4b50 100644 > --- a/kernel/kthread.c > +++ b/kernel/kthread.c > @@ -55,7 +55,6 @@ struct kthread { > int result; > int (*threadfn)(void *); > void *data; > - mm_segment_t oldfs; > struct completion parked; > struct completion exited; > #ifdef CONFIG_BLK_CGROUP > @@ -1441,8 +1440,6 @@ void kthread_use_mm(struct mm_struct *mm) > mmdrop(active_mm); > else > smp_mb(); > - > - to_kthread(tsk)->oldfs = force_uaccess_begin(); > } > EXPORT_SYMBOL_GPL(kthread_use_mm); > > @@ -1457,8 +1454,6 @@ void kthread_unuse_mm(struct mm_struct *mm) > WARN_ON_ONCE(!(tsk->flags & PF_KTHREAD)); > WARN_ON_ONCE(!tsk->mm); > > - force_uaccess_end(to_kthread(tsk)->oldfs); > - > task_lock(tsk); > /* > * When a kthread stops operating on an address space, the loop 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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6B027C433F5 for ; Thu, 17 Feb 2022 22:37:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Subject:MIME-Version:Message-ID: In-Reply-To:Date:References:Cc:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=OYNp1iDv/z5HQrLsl+tpZsvIkdRYRKStCdVcwKF2uzk=; b=rCBNMXl8T21OCiBcISvNpgxqMx IkoP3wdT9DOcSAjgs5mAJIfTox0VrM+/zp1pi2Vd3HiXoJGLF0qJLPgpFiZCD00H9olhCmImBGGUd HFK7KkQK3Co1BKYZg2YSByjnDacqTOQfpSMDpXeq6QKtmgw3wdhkc89u4XnXP5pUNHVRBFJLVpvyP RInXjLaFxBz3znFnIuR5tAPuRehe/51nihMpEFBx7eOdtRW7jIDPjiIm1GdGmdwjeJ3EKft9AYw+D fC3UqgFK03y9iN1r/m/cWnM/jPVOj8Nl2cpJtNRTELhmrBTyYPhd0a0neZYIfqKRIfb8oAEb3xAda 8RccrUkg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nKpOm-00CNLp-5F; Thu, 17 Feb 2022 22:37:16 +0000 Received: from out01.mta.xmission.com ([166.70.13.231]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nKpOi-00CNI2-BD; Thu, 17 Feb 2022 22:37:13 +0000 Received: from in02.mta.xmission.com ([166.70.13.52]:48942) by out01.mta.xmission.com with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1nKpOJ-001bK3-23; Thu, 17 Feb 2022 15:36:47 -0700 Received: from ip68-227-174-4.om.om.cox.net ([68.227.174.4]:32906 helo=email.froward.int.ebiederm.org.xmission.com) by in02.mta.xmission.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1nKpOG-00GKIm-Md; Thu, 17 Feb 2022 15:36:46 -0700 From: "Eric W. Biederman" To: Arnd Bergmann Cc: Linus Torvalds , Christoph Hellwig , linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-api@vger.kernel.org, arnd@arndb.de, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk, linux@armlinux.org.uk, will@kernel.org, guoren@kernel.org, bcain@codeaurora.org, geert@linux-m68k.org, monstr@monstr.eu, tsbogend@alpha.franken.de, nickhu@andestech.com, green.hu@gmail.com, dinguyen@kernel.org, shorne@gmail.com, deller@gmx.de, mpe@ellerman.id.au, peterz@infradead.org, mingo@redhat.com, mark.rutland@arm.com, hca@linux.ibm.com, dalias@libc.org, davem@davemloft.net, richard@nod.at, x86@kernel.org, jcmvbkbc@gmail.com, akpm@linux-foundation.org, ardb@kernel.org, linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org References: <20220216131332.1489939-1-arnd@kernel.org> <20220216131332.1489939-19-arnd@kernel.org> Date: Thu, 17 Feb 2022 16:36:20 -0600 In-Reply-To: <20220216131332.1489939-19-arnd@kernel.org> (Arnd Bergmann's message of "Wed, 16 Feb 2022 14:13:32 +0100") Message-ID: <8735khi0ij.fsf@email.froward.int.ebiederm.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 X-XM-SPF: eid=1nKpOG-00GKIm-Md; ; ; mid=<8735khi0ij.fsf@email.froward.int.ebiederm.org>; ; ; hst=in02.mta.xmission.com; ; ; ip=68.227.174.4; ; ; frm=ebiederm@xmission.com; ; ; spf=neutral X-XM-AID: U2FsdGVkX1/V+0C7NWKuSkdwXmdluwhE5ZIu3hq7L5I= X-SA-Exim-Connect-IP: 68.227.174.4 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: Re: [PATCH v2 18/18] uaccess: drop maining CONFIG_SET_FS users X-SA-Exim-Version: 4.2.1 (built Sat, 08 Feb 2020 21:53:50 +0000) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220217_143712_396361_9B9127DD X-CRM114-Status: GOOD ( 21.88 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org Arnd Bergmann writes: > From: Arnd Bergmann > > There are no remaining callers of set_fs(), so CONFIG_SET_FS > can be removed globally, along with the thread_info field and > any references to it. > > This turns access_ok() into a cheaper check against TASK_SIZE_MAX. > > With CONFIG_SET_FS gone, so drop all remaining references to > set_fs()/get_fs(), mm_segment_t and uaccess_kernel(). For the bits I have looked at recently, and think I understand. Acked-by: "Eric W. Biederman" > > Signed-off-by: Arnd Bergmann > --- > fs/exec.c | 6 -- > kernel/exit.c | 14 ----- > kernel/kthread.c | 5 -- > > diff --git a/fs/exec.c b/fs/exec.c > index 79f2c9483302..bc68a0c089ac 100644 > --- a/fs/exec.c > +++ b/fs/exec.c > @@ -1303,12 +1303,6 @@ int begin_new_exec(struct linux_binprm * bprm) > if (retval) > goto out_unlock; > > - /* > - * Ensure that the uaccess routines can actually operate on userspace > - * pointers: > - */ > - force_uaccess_begin(); > - > if (me->flags & PF_KTHREAD) > free_kthread_struct(me); > me->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD | > diff --git a/kernel/exit.c b/kernel/exit.c > index b00a25bb4ab9..0884a75bc2f8 100644 > --- a/kernel/exit.c > +++ b/kernel/exit.c > @@ -737,20 +737,6 @@ void __noreturn do_exit(long code) > > WARN_ON(blk_needs_flush_plug(tsk)); > > - /* > - * If do_dead is called because this processes oopsed, it's possible > - * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before > - * continuing. Amongst other possible reasons, this is to prevent > - * mm_release()->clear_child_tid() from writing to a user-controlled > - * kernel address. > - * > - * On uptodate architectures force_uaccess_begin is a noop. On > - * architectures that still have set_fs/get_fs in addition to handling > - * oopses handles kernel threads that run as set_fs(KERNEL_DS) by > - * default. > - */ > - force_uaccess_begin(); > - > kcov_task_exit(tsk); > > coredump_task_exit(tsk); > diff --git a/kernel/kthread.c b/kernel/kthread.c > index 38c6dd822da8..16c2275d4b50 100644 > --- a/kernel/kthread.c > +++ b/kernel/kthread.c > @@ -55,7 +55,6 @@ struct kthread { > int result; > int (*threadfn)(void *); > void *data; > - mm_segment_t oldfs; > struct completion parked; > struct completion exited; > #ifdef CONFIG_BLK_CGROUP > @@ -1441,8 +1440,6 @@ void kthread_use_mm(struct mm_struct *mm) > mmdrop(active_mm); > else > smp_mb(); > - > - to_kthread(tsk)->oldfs = force_uaccess_begin(); > } > EXPORT_SYMBOL_GPL(kthread_use_mm); > > @@ -1457,8 +1454,6 @@ void kthread_unuse_mm(struct mm_struct *mm) > WARN_ON_ONCE(!(tsk->flags & PF_KTHREAD)); > WARN_ON_ONCE(!tsk->mm); > > - force_uaccess_end(to_kthread(tsk)->oldfs); > - > task_lock(tsk); > /* > * When a kthread stops operating on an address space, the loop _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv 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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5A70FC433EF for ; Thu, 17 Feb 2022 22:37:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Subject:MIME-Version:Message-ID: In-Reply-To:Date:References:Cc:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=+Nx27V7GQ/IiK1uTEW1Sjg6JsVLQGKmASOdHmjROYD0=; b=N6E6Go6ddm4LltJfaOqddjZfRi EzliE86RmSKqLP5hdV9Fpms84j8mMZKUSiU14bk8SE7cgl7cUVyjTCmaI4Yzk72XN1cjajOcufXcG XU5GttGZORBLtYbfkip8ltYZysiKYRQP6RhehKQ8pf1Ysz1tXksqvMYlPTxBgU1KIv6Wk2aBeoDdQ EjlL9pMUO5jxSfhCAdc8uOQOxqQvehXuY4FKyLlDH6HuPuWgvH9GA7F1IKHhXD+EhdTtCGl1YFWcN vSdsNw2NBgZUCWvymDZ0l6yuJ4g7QDOWIp8IHzY/xogJkwHDs0gNVuLoqkbPPPMbAX8tS9xaC59ia ALiHqW5w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nKpOn-00CNMc-V1; Thu, 17 Feb 2022 22:37:17 +0000 Received: from out01.mta.xmission.com ([166.70.13.231]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nKpOi-00CNI2-BD; Thu, 17 Feb 2022 22:37:13 +0000 Received: from in02.mta.xmission.com ([166.70.13.52]:48942) by out01.mta.xmission.com with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1nKpOJ-001bK3-23; Thu, 17 Feb 2022 15:36:47 -0700 Received: from ip68-227-174-4.om.om.cox.net ([68.227.174.4]:32906 helo=email.froward.int.ebiederm.org.xmission.com) by in02.mta.xmission.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1nKpOG-00GKIm-Md; Thu, 17 Feb 2022 15:36:46 -0700 From: "Eric W. Biederman" To: Arnd Bergmann Cc: Linus Torvalds , Christoph Hellwig , linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-api@vger.kernel.org, arnd@arndb.de, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk, linux@armlinux.org.uk, will@kernel.org, guoren@kernel.org, bcain@codeaurora.org, geert@linux-m68k.org, monstr@monstr.eu, tsbogend@alpha.franken.de, nickhu@andestech.com, green.hu@gmail.com, dinguyen@kernel.org, shorne@gmail.com, deller@gmx.de, mpe@ellerman.id.au, peterz@infradead.org, mingo@redhat.com, mark.rutland@arm.com, hca@linux.ibm.com, dalias@libc.org, davem@davemloft.net, richard@nod.at, x86@kernel.org, jcmvbkbc@gmail.com, akpm@linux-foundation.org, ardb@kernel.org, linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org References: <20220216131332.1489939-1-arnd@kernel.org> <20220216131332.1489939-19-arnd@kernel.org> Date: Thu, 17 Feb 2022 16:36:20 -0600 In-Reply-To: <20220216131332.1489939-19-arnd@kernel.org> (Arnd Bergmann's message of "Wed, 16 Feb 2022 14:13:32 +0100") Message-ID: <8735khi0ij.fsf@email.froward.int.ebiederm.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 X-XM-SPF: eid=1nKpOG-00GKIm-Md; ; ; mid=<8735khi0ij.fsf@email.froward.int.ebiederm.org>; ; ; hst=in02.mta.xmission.com; ; ; ip=68.227.174.4; ; ; frm=ebiederm@xmission.com; ; ; spf=neutral X-XM-AID: U2FsdGVkX1/V+0C7NWKuSkdwXmdluwhE5ZIu3hq7L5I= X-SA-Exim-Connect-IP: 68.227.174.4 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: Re: [PATCH v2 18/18] uaccess: drop maining CONFIG_SET_FS users X-SA-Exim-Version: 4.2.1 (built Sat, 08 Feb 2020 21:53:50 +0000) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220217_143712_396361_9B9127DD X-CRM114-Status: GOOD ( 21.88 ) X-BeenThere: linux-snps-arc@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux on Synopsys ARC Processors List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-snps-arc" Errors-To: linux-snps-arc-bounces+linux-snps-arc=archiver.kernel.org@lists.infradead.org Arnd Bergmann writes: > From: Arnd Bergmann > > There are no remaining callers of set_fs(), so CONFIG_SET_FS > can be removed globally, along with the thread_info field and > any references to it. > > This turns access_ok() into a cheaper check against TASK_SIZE_MAX. > > With CONFIG_SET_FS gone, so drop all remaining references to > set_fs()/get_fs(), mm_segment_t and uaccess_kernel(). For the bits I have looked at recently, and think I understand. Acked-by: "Eric W. Biederman" > > Signed-off-by: Arnd Bergmann > --- > fs/exec.c | 6 -- > kernel/exit.c | 14 ----- > kernel/kthread.c | 5 -- > > diff --git a/fs/exec.c b/fs/exec.c > index 79f2c9483302..bc68a0c089ac 100644 > --- a/fs/exec.c > +++ b/fs/exec.c > @@ -1303,12 +1303,6 @@ int begin_new_exec(struct linux_binprm * bprm) > if (retval) > goto out_unlock; > > - /* > - * Ensure that the uaccess routines can actually operate on userspace > - * pointers: > - */ > - force_uaccess_begin(); > - > if (me->flags & PF_KTHREAD) > free_kthread_struct(me); > me->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD | > diff --git a/kernel/exit.c b/kernel/exit.c > index b00a25bb4ab9..0884a75bc2f8 100644 > --- a/kernel/exit.c > +++ b/kernel/exit.c > @@ -737,20 +737,6 @@ void __noreturn do_exit(long code) > > WARN_ON(blk_needs_flush_plug(tsk)); > > - /* > - * If do_dead is called because this processes oopsed, it's possible > - * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before > - * continuing. Amongst other possible reasons, this is to prevent > - * mm_release()->clear_child_tid() from writing to a user-controlled > - * kernel address. > - * > - * On uptodate architectures force_uaccess_begin is a noop. On > - * architectures that still have set_fs/get_fs in addition to handling > - * oopses handles kernel threads that run as set_fs(KERNEL_DS) by > - * default. > - */ > - force_uaccess_begin(); > - > kcov_task_exit(tsk); > > coredump_task_exit(tsk); > diff --git a/kernel/kthread.c b/kernel/kthread.c > index 38c6dd822da8..16c2275d4b50 100644 > --- a/kernel/kthread.c > +++ b/kernel/kthread.c > @@ -55,7 +55,6 @@ struct kthread { > int result; > int (*threadfn)(void *); > void *data; > - mm_segment_t oldfs; > struct completion parked; > struct completion exited; > #ifdef CONFIG_BLK_CGROUP > @@ -1441,8 +1440,6 @@ void kthread_use_mm(struct mm_struct *mm) > mmdrop(active_mm); > else > smp_mb(); > - > - to_kthread(tsk)->oldfs = force_uaccess_begin(); > } > EXPORT_SYMBOL_GPL(kthread_use_mm); > > @@ -1457,8 +1454,6 @@ void kthread_unuse_mm(struct mm_struct *mm) > WARN_ON_ONCE(!(tsk->flags & PF_KTHREAD)); > WARN_ON_ONCE(!tsk->mm); > > - force_uaccess_end(to_kthread(tsk)->oldfs); > - > task_lock(tsk); > /* > * When a kthread stops operating on an address space, the loop _______________________________________________ linux-snps-arc mailing list linux-snps-arc@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-snps-arc From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric W. Biederman Date: Thu, 17 Feb 2022 16:36:20 -0600 Subject: [OpenRISC] [PATCH v2 18/18] uaccess: drop maining CONFIG_SET_FS users In-Reply-To: <20220216131332.1489939-19-arnd@kernel.org> (Arnd Bergmann's message of "Wed, 16 Feb 2022 14:13:32 +0100") References: <20220216131332.1489939-1-arnd@kernel.org> <20220216131332.1489939-19-arnd@kernel.org> Message-ID: <8735khi0ij.fsf@email.froward.int.ebiederm.org> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: openrisc@lists.librecores.org Arnd Bergmann writes: > From: Arnd Bergmann > > There are no remaining callers of set_fs(), so CONFIG_SET_FS > can be removed globally, along with the thread_info field and > any references to it. > > This turns access_ok() into a cheaper check against TASK_SIZE_MAX. > > With CONFIG_SET_FS gone, so drop all remaining references to > set_fs()/get_fs(), mm_segment_t and uaccess_kernel(). For the bits I have looked at recently, and think I understand. Acked-by: "Eric W. Biederman" > > Signed-off-by: Arnd Bergmann > --- > fs/exec.c | 6 -- > kernel/exit.c | 14 ----- > kernel/kthread.c | 5 -- > > diff --git a/fs/exec.c b/fs/exec.c > index 79f2c9483302..bc68a0c089ac 100644 > --- a/fs/exec.c > +++ b/fs/exec.c > @@ -1303,12 +1303,6 @@ int begin_new_exec(struct linux_binprm * bprm) > if (retval) > goto out_unlock; > > - /* > - * Ensure that the uaccess routines can actually operate on userspace > - * pointers: > - */ > - force_uaccess_begin(); > - > if (me->flags & PF_KTHREAD) > free_kthread_struct(me); > me->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD | > diff --git a/kernel/exit.c b/kernel/exit.c > index b00a25bb4ab9..0884a75bc2f8 100644 > --- a/kernel/exit.c > +++ b/kernel/exit.c > @@ -737,20 +737,6 @@ void __noreturn do_exit(long code) > > WARN_ON(blk_needs_flush_plug(tsk)); > > - /* > - * If do_dead is called because this processes oopsed, it's possible > - * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before > - * continuing. Amongst other possible reasons, this is to prevent > - * mm_release()->clear_child_tid() from writing to a user-controlled > - * kernel address. > - * > - * On uptodate architectures force_uaccess_begin is a noop. On > - * architectures that still have set_fs/get_fs in addition to handling > - * oopses handles kernel threads that run as set_fs(KERNEL_DS) by > - * default. > - */ > - force_uaccess_begin(); > - > kcov_task_exit(tsk); > > coredump_task_exit(tsk); > diff --git a/kernel/kthread.c b/kernel/kthread.c > index 38c6dd822da8..16c2275d4b50 100644 > --- a/kernel/kthread.c > +++ b/kernel/kthread.c > @@ -55,7 +55,6 @@ struct kthread { > int result; > int (*threadfn)(void *); > void *data; > - mm_segment_t oldfs; > struct completion parked; > struct completion exited; > #ifdef CONFIG_BLK_CGROUP > @@ -1441,8 +1440,6 @@ void kthread_use_mm(struct mm_struct *mm) > mmdrop(active_mm); > else > smp_mb(); > - > - to_kthread(tsk)->oldfs = force_uaccess_begin(); > } > EXPORT_SYMBOL_GPL(kthread_use_mm); > > @@ -1457,8 +1454,6 @@ void kthread_unuse_mm(struct mm_struct *mm) > WARN_ON_ONCE(!(tsk->flags & PF_KTHREAD)); > WARN_ON_ONCE(!tsk->mm); > > - force_uaccess_end(to_kthread(tsk)->oldfs); > - > task_lock(tsk); > /* > * When a kthread stops operating on an address space, the loop 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 Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8CDC6C433F5 for ; Thu, 17 Feb 2022 22:54:44 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4K09BV40dRz3cbb for ; Fri, 18 Feb 2022 09:54:42 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=xmission.com (client-ip=166.70.13.231; helo=out01.mta.xmission.com; envelope-from=ebiederm@xmission.com; receiver=) X-Greylist: delayed 1032 seconds by postgrey-1.36 at boromir; Fri, 18 Feb 2022 09:54:13 AEDT Received: from out01.mta.xmission.com (out01.mta.xmission.com [166.70.13.231]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4K099x2wDfz2x9V for ; Fri, 18 Feb 2022 09:54:13 +1100 (AEDT) Received: from in02.mta.xmission.com ([166.70.13.52]:48942) by out01.mta.xmission.com with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1nKpOJ-001bK3-23; Thu, 17 Feb 2022 15:36:47 -0700 Received: from ip68-227-174-4.om.om.cox.net ([68.227.174.4]:32906 helo=email.froward.int.ebiederm.org.xmission.com) by in02.mta.xmission.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1nKpOG-00GKIm-Md; Thu, 17 Feb 2022 15:36:46 -0700 From: "Eric W. Biederman" To: Arnd Bergmann References: <20220216131332.1489939-1-arnd@kernel.org> <20220216131332.1489939-19-arnd@kernel.org> Date: Thu, 17 Feb 2022 16:36:20 -0600 In-Reply-To: <20220216131332.1489939-19-arnd@kernel.org> (Arnd Bergmann's message of "Wed, 16 Feb 2022 14:13:32 +0100") Message-ID: <8735khi0ij.fsf@email.froward.int.ebiederm.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1nKpOG-00GKIm-Md; ; ; mid=<8735khi0ij.fsf@email.froward.int.ebiederm.org>; ; ; hst=in02.mta.xmission.com; ; ; ip=68.227.174.4; ; ; frm=ebiederm@xmission.com; ; ; spf=neutral X-XM-AID: U2FsdGVkX1/V+0C7NWKuSkdwXmdluwhE5ZIu3hq7L5I= X-SA-Exim-Connect-IP: 68.227.174.4 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: Re: [PATCH v2 18/18] uaccess: drop maining CONFIG_SET_FS users X-SA-Exim-Version: 4.2.1 (built Sat, 08 Feb 2020 21:53:50 +0000) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, dalias@libc.org, linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, peterz@infradead.org, linux-mips@vger.kernel.org, linux-mm@kvack.org, guoren@kernel.org, sparclinux@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-riscv@lists.infradead.org, will@kernel.org, Christoph Hellwig , linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, bcain@codeaurora.org, deller@gmx.de, x86@kernel.org, linux@armlinux.org.uk, linux-csky@vger.kernel.org, ardb@kernel.org, mingo@redhat.com, geert@linux-m68k.org, linux-snps-arc@lists.infradead.org, linux-xtensa@linux-xtensa.org, arnd@arndb.de, hca@linux.ibm.com, linux-alpha@vger.kernel.org, linux-um@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-m68k@lists.linux-m68k.org, openrisc@lists.librecores.org, viro@zeniv.linux.org.uk, shorne@gmail.com, monstr@monstr.eu, tsbogend@alpha.franken.de, linux-parisc@vger.kernel.org, nickhu@andestech.com, jcmvbkbc@gmail.com, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, dinguyen@kernel.org, richard@nod.at, akpm@linux-foundation.org, Linus Torvalds , davem@davemloft.net, green.hu@gmail.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Arnd Bergmann writes: > From: Arnd Bergmann > > There are no remaining callers of set_fs(), so CONFIG_SET_FS > can be removed globally, along with the thread_info field and > any references to it. > > This turns access_ok() into a cheaper check against TASK_SIZE_MAX. > > With CONFIG_SET_FS gone, so drop all remaining references to > set_fs()/get_fs(), mm_segment_t and uaccess_kernel(). For the bits I have looked at recently, and think I understand. Acked-by: "Eric W. Biederman" > > Signed-off-by: Arnd Bergmann > --- > fs/exec.c | 6 -- > kernel/exit.c | 14 ----- > kernel/kthread.c | 5 -- > > diff --git a/fs/exec.c b/fs/exec.c > index 79f2c9483302..bc68a0c089ac 100644 > --- a/fs/exec.c > +++ b/fs/exec.c > @@ -1303,12 +1303,6 @@ int begin_new_exec(struct linux_binprm * bprm) > if (retval) > goto out_unlock; > > - /* > - * Ensure that the uaccess routines can actually operate on userspace > - * pointers: > - */ > - force_uaccess_begin(); > - > if (me->flags & PF_KTHREAD) > free_kthread_struct(me); > me->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD | > diff --git a/kernel/exit.c b/kernel/exit.c > index b00a25bb4ab9..0884a75bc2f8 100644 > --- a/kernel/exit.c > +++ b/kernel/exit.c > @@ -737,20 +737,6 @@ void __noreturn do_exit(long code) > > WARN_ON(blk_needs_flush_plug(tsk)); > > - /* > - * If do_dead is called because this processes oopsed, it's possible > - * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before > - * continuing. Amongst other possible reasons, this is to prevent > - * mm_release()->clear_child_tid() from writing to a user-controlled > - * kernel address. > - * > - * On uptodate architectures force_uaccess_begin is a noop. On > - * architectures that still have set_fs/get_fs in addition to handling > - * oopses handles kernel threads that run as set_fs(KERNEL_DS) by > - * default. > - */ > - force_uaccess_begin(); > - > kcov_task_exit(tsk); > > coredump_task_exit(tsk); > diff --git a/kernel/kthread.c b/kernel/kthread.c > index 38c6dd822da8..16c2275d4b50 100644 > --- a/kernel/kthread.c > +++ b/kernel/kthread.c > @@ -55,7 +55,6 @@ struct kthread { > int result; > int (*threadfn)(void *); > void *data; > - mm_segment_t oldfs; > struct completion parked; > struct completion exited; > #ifdef CONFIG_BLK_CGROUP > @@ -1441,8 +1440,6 @@ void kthread_use_mm(struct mm_struct *mm) > mmdrop(active_mm); > else > smp_mb(); > - > - to_kthread(tsk)->oldfs = force_uaccess_begin(); > } > EXPORT_SYMBOL_GPL(kthread_use_mm); > > @@ -1457,8 +1454,6 @@ void kthread_unuse_mm(struct mm_struct *mm) > WARN_ON_ONCE(!(tsk->flags & PF_KTHREAD)); > WARN_ON_ONCE(!tsk->mm); > > - force_uaccess_end(to_kthread(tsk)->oldfs); > - > task_lock(tsk); > /* > * When a kthread stops operating on an address space, the loop