From patchwork Tue Apr 5 07:21:52 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 557116 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 BEE11C47082 for ; Tue, 5 Apr 2022 11:04:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242800AbiDEK51 (ORCPT ); Tue, 5 Apr 2022 06:57:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60854 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346689AbiDEJpV (ORCPT ); Tue, 5 Apr 2022 05:45:21 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2443B2B26A; Tue, 5 Apr 2022 02:31:22 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id AABD3616D0; Tue, 5 Apr 2022 09:31:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B526AC385A6; Tue, 5 Apr 2022 09:31:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649151081; bh=lsQCMO2UAmOUxU32IZI7RqfmRogOdDAJkU+iTVAqMEs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AYrEvcXdb31UH39ZTuwyquUpTv4ymnTPJ82GoZbLGEzvtXWRgfWb4g0h0sRxOc+U2 eJYhUfUnP0+jUd0NgR2FqciqUgR2l+7b9w7ayNNcm3dVpdEGoFkoCuq7qilJLSrBAe u9/BcyfWdmKEbYtu1QfDT/3RfBmD5QRYSlcxK5YI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mathieu Desnoyers , "Peter Zijlstra (Intel)" , Sasha Levin Subject: [PATCH 5.15 250/913] rseq: Remove broken uapi field layout on 32-bit little endian Date: Tue, 5 Apr 2022 09:21:52 +0200 Message-Id: <20220405070347.351013947@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220405070339.801210740@linuxfoundation.org> References: <20220405070339.801210740@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Mathieu Desnoyers [ Upstream commit bfdf4e6208051ed7165b2e92035b4bf11f43eb63 ] The rseq rseq_cs.ptr.{ptr32,padding} uapi endianness handling is entirely wrong on 32-bit little endian: a preprocessor logic mistake wrongly uses the big endian field layout on 32-bit little endian architectures. Fortunately, those ptr32 accessors were never used within the kernel, and only meant as a convenience for user-space. Remove those and replace the whole rseq_cs union by a __u64 type, as this is the only thing really needed to express the ABI. Document how 32-bit architectures are meant to interact with this field. Fixes: ec9c82e03a74 ("rseq: uapi: Declare rseq_cs field as union, update includes") Signed-off-by: Mathieu Desnoyers Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20220127152720.25898-1-mathieu.desnoyers@efficios.com Signed-off-by: Sasha Levin --- include/uapi/linux/rseq.h | 20 ++++---------------- kernel/rseq.c | 8 ++++---- 2 files changed, 8 insertions(+), 20 deletions(-) diff --git a/include/uapi/linux/rseq.h b/include/uapi/linux/rseq.h index 9a402fdb60e9..77ee207623a9 100644 --- a/include/uapi/linux/rseq.h +++ b/include/uapi/linux/rseq.h @@ -105,23 +105,11 @@ struct rseq { * Read and set by the kernel. Set by user-space with single-copy * atomicity semantics. This field should only be updated by the * thread which registered this data structure. Aligned on 64-bit. + * + * 32-bit architectures should update the low order bits of the + * rseq_cs field, leaving the high order bits initialized to 0. */ - union { - __u64 ptr64; -#ifdef __LP64__ - __u64 ptr; -#else - struct { -#if (defined(__BYTE_ORDER) && (__BYTE_ORDER == __BIG_ENDIAN)) || defined(__BIG_ENDIAN) - __u32 padding; /* Initialized to zero. */ - __u32 ptr32; -#else /* LITTLE */ - __u32 ptr32; - __u32 padding; /* Initialized to zero. */ -#endif /* ENDIAN */ - } ptr; -#endif - } rseq_cs; + __u64 rseq_cs; /* * Restartable sequences flags field. diff --git a/kernel/rseq.c b/kernel/rseq.c index 6d45ac3dae7f..97ac20b4f738 100644 --- a/kernel/rseq.c +++ b/kernel/rseq.c @@ -128,10 +128,10 @@ static int rseq_get_rseq_cs(struct task_struct *t, struct rseq_cs *rseq_cs) int ret; #ifdef CONFIG_64BIT - if (get_user(ptr, &t->rseq->rseq_cs.ptr64)) + if (get_user(ptr, &t->rseq->rseq_cs)) return -EFAULT; #else - if (copy_from_user(&ptr, &t->rseq->rseq_cs.ptr64, sizeof(ptr))) + if (copy_from_user(&ptr, &t->rseq->rseq_cs, sizeof(ptr))) return -EFAULT; #endif if (!ptr) { @@ -217,9 +217,9 @@ static int clear_rseq_cs(struct task_struct *t) * Set rseq_cs to NULL. */ #ifdef CONFIG_64BIT - return put_user(0UL, &t->rseq->rseq_cs.ptr64); + return put_user(0UL, &t->rseq->rseq_cs); #else - if (clear_user(&t->rseq->rseq_cs.ptr64, sizeof(t->rseq->rseq_cs.ptr64))) + if (clear_user(&t->rseq->rseq_cs, sizeof(t->rseq->rseq_cs))) return -EFAULT; return 0; #endif