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 2A511C76196 for ; Wed, 22 Mar 2023 20:12:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232125AbjCVUMF (ORCPT ); Wed, 22 Mar 2023 16:12:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50460 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231978AbjCVULd (ORCPT ); Wed, 22 Mar 2023 16:11:33 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C3A196A1DE; Wed, 22 Mar 2023 13:03:56 -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 ams.source.kernel.org (Postfix) with ESMTPS id 5B824B81DE7; Wed, 22 Mar 2023 20:03:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2B340C433EF; Wed, 22 Mar 2023 20:03:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1679515435; bh=8QbxsXfcTm2I1rjmgYFq133a78vKmloy1VABp7AA8HY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Zruc9OAB1EpU8hj3mDXiqw/OhGnK+PS2dguoSdqOvm8GYolg4Pz5zdh675wKjwqAp ladgksZXiEAk4oqXc6wFhTIfkbv1L4cQzaZX/OWQ+3i3H+DCWnTfMGGb77USxkNrKi BBvXXmd2SvbcvALwNdrYL/fqZBK9DsBfqHEpOn36YLRzQIVtxoMGxa4HL9m4IHimP+ QIdno34V+F/Qza5cOasIp93aSI24c61ShHRn6MhLB726a49+5mkleFBEuOIwlSYb8+ iWCM3GKadE0R8R7WK7wnitSdzjLEtNCH+LaNdYyjTmV2pv/BwBNFzEJYcNyMpzmkmy NFdI3IJOz2b3w== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Linus Torvalds , Ryan Roberts , Yury Norov , Sasha Levin , mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org Subject: [PATCH AUTOSEL 4.14 5/9] sched_getaffinity: don't assume 'cpumask_size()' is fully initialized Date: Wed, 22 Mar 2023 16:03:32 -0400 Message-Id: <20230322200337.1997810-5-sashal@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230322200337.1997810-1-sashal@kernel.org> References: <20230322200337.1997810-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Linus Torvalds [ Upstream commit 6015b1aca1a233379625385feb01dd014aca60b5 ] The getaffinity() system call uses 'cpumask_size()' to decide how big the CPU mask is - so far so good. It is indeed the allocation size of a cpumask. But the code also assumes that the whole allocation is initialized without actually doing so itself. That's wrong, because we might have fixed-size allocations (making copying and clearing more efficient), but not all of it is then necessarily used if 'nr_cpu_ids' is smaller. Having checked other users of 'cpumask_size()', they all seem to be ok, either using it purely for the allocation size, or explicitly zeroing the cpumask before using the size in bytes to copy it. See for example the ublk_ctrl_get_queue_affinity() function that uses the proper 'zalloc_cpumask_var()' to make sure that the whole mask is cleared, whether the storage is on the stack or if it was an external allocation. Fix this by just zeroing the allocation before using it. Do the same for the compat version of sched_getaffinity(), which had the same logic. Also, for consistency, make sched_getaffinity() use 'cpumask_bits()' to access the bits. For a cpumask_var_t, it ends up being a pointer to the same data either way, but it's just a good idea to treat it like you would a 'cpumask_t'. The compat case already did that. Reported-by: Ryan Roberts Link: https://lore.kernel.org/lkml/7d026744-6bd6-6827-0471-b5e8eae0be3f@arm.com/ Cc: Yury Norov Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- kernel/compat.c | 2 +- kernel/sched/core.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/kernel/compat.c b/kernel/compat.c index 45ae3ace49c29..63d10b91f80fa 100644 --- a/kernel/compat.c +++ b/kernel/compat.c @@ -351,7 +351,7 @@ COMPAT_SYSCALL_DEFINE3(sched_getaffinity, compat_pid_t, pid, unsigned int, len, if (len & (sizeof(compat_ulong_t)-1)) return -EINVAL; - if (!alloc_cpumask_var(&mask, GFP_KERNEL)) + if (!zalloc_cpumask_var(&mask, GFP_KERNEL)) return -ENOMEM; ret = sched_getaffinity(pid, mask); diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 5dc66377864a9..b4390a860e110 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4791,14 +4791,14 @@ SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len, if (len & (sizeof(unsigned long)-1)) return -EINVAL; - if (!alloc_cpumask_var(&mask, GFP_KERNEL)) + if (!zalloc_cpumask_var(&mask, GFP_KERNEL)) return -ENOMEM; ret = sched_getaffinity(pid, mask); if (ret == 0) { size_t retlen = min_t(size_t, len, cpumask_size()); - if (copy_to_user(user_mask_ptr, mask, retlen)) + if (copy_to_user(user_mask_ptr, cpumask_bits(mask), retlen)) ret = -EFAULT; else ret = retlen; -- 2.39.2