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 A1CD439B946 for ; Sat, 28 Feb 2026 18:16:18 +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=1772302578; cv=none; b=dKArFvR23KUGLhf8O2iMZGSMPOylfWgzDJSGQn1XaOmWx+Se1tjy/PpHxQBtZWGipipHHro9zlqjQ2nx5bGeXbDfaxEnWwCldS5cOPPEhJfkxlQqVNMVQmJFttvpn9a50cRXgawmwYmspz7Vu5NyugD8U+zCHQij58r6PYBN+AM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772302578; c=relaxed/simple; bh=yDvifsN7wAWrjkIo4s1cEOf9dhIFtifUSK2nXgGOghU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=qTwiTNs4N7rrSOzcLbvg1vjjG1+P/pqzpElKK1LTgYehIyeqGmX3xRTUyfsXd3alf+QXzFNL0i+l4NP76j7ptdpMvxI3ZNAvyQxiYRhLDn+OBoftXSjy+zT1GQlf3x+kwSZkwjZ+bLeW6DRTOZujFAEl3BSvQbCT9X9FuvOAL50= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=NBg244nB; 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="NBg244nB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 72799C19425; Sat, 28 Feb 2026 18:16:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772302578; bh=yDvifsN7wAWrjkIo4s1cEOf9dhIFtifUSK2nXgGOghU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NBg244nBFvk6ZdGTJ0T96uav3aDW+LsqAV/s3NRGQEUg1WSWC8hI8AO1+mZjpa0EX 8K6SdZZZrCdu4ceZ0lsd0pmhhEZuMD/mdm8nkJK9qTj2KTjxQEzmT4V2uVSrVGdEbi 56c8a5htvT5E97fMzyk4JGleOfVSp5sXBVYOUqM5BDzuJHm0Lyq1TLQbUDqpKxaFuk l8S9Q/lHRSiBGL0r7w5jZBDk5KYUmGcqe0hbRetP2/3GAnyNHNOwr1Ki24GG2RzBJL KYravzifqqv7eZXmSeqoMfqj0pMwY936ofXMICIetvYXCdeKFvi+RX9tGyZ8YGFAhJ IqNxua/a9lwaA== From: Sasha Levin To: patches@lists.linux.dev Cc: Jinliang Zheng , Oleg Nesterov , David Hildenbrand , Ingo Molnar , Lorenzo Stoakes , Mateusz Guzik , ruippan , Usama Arif , Andrew Morton , Sasha Levin Subject: [PATCH 5.15 086/164] procfs: fix missing RCU protection when reading real_parent in do_task_stat() Date: Sat, 28 Feb 2026 13:13:45 -0500 Message-ID: <20260228181505.1600663-86-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260228181505.1600663-1-sashal@kernel.org> References: <20260228181505.1600663-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit From: Jinliang Zheng [ Upstream commit 76149d53502cf17ef3ae454ff384551236fba867 ] When reading /proc/[pid]/stat, do_task_stat() accesses task->real_parent without proper RCU protection, which leads to: cpu 0 cpu 1 ----- ----- do_task_stat var = task->real_parent release_task call_rcu(delayed_put_task_struct) task_tgid_nr_ns(var) rcu_read_lock <--- Too late to protect task->real_parent! task_pid_ptr <--- UAF! rcu_read_unlock This patch uses task_ppid_nr_ns() instead of task_tgid_nr_ns() to add proper RCU protection for accessing task->real_parent. Link: https://lkml.kernel.org/r/20260128083007.3173016-1-alexjlzheng@tencent.com Fixes: 06fffb1267c9 ("do_task_stat: don't take rcu_read_lock()") Signed-off-by: Jinliang Zheng Acked-by: Oleg Nesterov Cc: David Hildenbrand Cc: Ingo Molnar Cc: Lorenzo Stoakes Cc: Mateusz Guzik Cc: ruippan Cc: Usama Arif Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin --- fs/proc/array.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/proc/array.c b/fs/proc/array.c index 2ff568dc58387..6f30b5a316678 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -510,7 +510,7 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns, rsslim = READ_ONCE(sig->rlim[RLIMIT_RSS].rlim_cur); sid = task_session_nr_ns(task, ns); - ppid = task_tgid_nr_ns(task->real_parent, ns); + ppid = task_ppid_nr_ns(task, ns); pgid = task_pgrp_nr_ns(task, ns); unlock_task_sighand(task, &flags); -- 2.51.0