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 ED2BB359A71 for ; Sat, 28 Feb 2026 18:13:11 +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=1772302392; cv=none; b=oZ4ATbLH+GsLXhokinTLarCteG2xcKLhYKuJh60HdbM2sOQ05xrcRiFr3LdaCilmXgl43IwrPSb3sJeZRTD8rgsg7alFxhbUTNQBma5HfU3OJGfCDbLixCIgiYWlp5Ur6YNVufqtBUtjIG2aEBPD02XwvTZVrRQuxpwgU7/GIx8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772302392; c=relaxed/simple; bh=BW4359koPPADY/wV50PnCPM/JDDWYVGT5qZzQELZwkc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Wy9tm3bX3BGX9lQQ+bLrf1VXqj3LANuqShUUTJVR8TUxPb4x1+4B+hU8nRi2C/iQJII/GU5O2KIaD/kigMyJanP385pdHKIje6bN3DJb2q+Woo6iJWSX/s0jX4Wt3lNGV+v+XZZv1+h/YVU4vBmUB0soX5xRSCMAJVHRN3bd8hI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=XnyrgCxM; 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="XnyrgCxM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B6D75C19425; Sat, 28 Feb 2026 18:13:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772302391; bh=BW4359koPPADY/wV50PnCPM/JDDWYVGT5qZzQELZwkc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XnyrgCxM16/EhFL/4krAPKbegEOusq2FiQJ+AHXWALnrFgViI+Z0j00BtVV8LIiBL sfOeYsOBtRV9FbiCa2it4gbi+jt+t9V510XxVHPOaC8gCW2slSoc2Nbs3uU4fJKZTM 0lmsUlu2xEnAEM9GvzpP5bdx5bBuO3ruY/ZoMs0RElpvmeG1ZuSb99hysuWWTShZDx f3rMXKOy4GfJfUt9391Vr7N2+cfVVhToFGlCZ6l7CHf8dRtv7zE6JppIZ9X9720ZKK HlPGnuvprFuG+kfzNooR5KnwoLP8az6zg2Tkq9JjdSSJOc6LJn2WhQ9HVVN+GSgWb7 DE5ol5s5mXycA== 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 6.1 121/232] procfs: fix missing RCU protection when reading real_parent in do_task_stat() Date: Sat, 28 Feb 2026 13:09:34 -0500 Message-ID: <20260228181127.1592657-121-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260228181127.1592657-1-sashal@kernel.org> References: <20260228181127.1592657-1-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 86fde69ec11a2..a3212f11a1b43 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -521,7 +521,7 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns, } 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