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 6C9C22C0F97; Wed, 25 Feb 2026 06:56:27 +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=1772002587; cv=none; b=OLdr6rz+Au+IaA8jL+bdqGL6fI3Mr41/HQ/OZ/OwMzSD5U5xsHHTVD3hU3zPHFui25smOemftuaVfjNI84cwJHgFpsBAeIxv4cfD3r4q36y7xRBtxUs0AfUWMjBgC/WAfLLr2YtKQUsi4TsuxUooO5xT1NPxKgKxHEpapRMpYEE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772002587; c=relaxed/simple; bh=Nof224jaw1S8dxPoH/9AIp/MoIv5D48FJF+tPwUhdfg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=efWRTx104XMIy7CPdlxU/mwruxdyLR+emK7WMmdnhSjkqim5Cv11YMey3KgFYEP2csHMDkmKIO4tnP4A2o/Jkyhuhe/fSxNiAxYMUgFHmMRlT6ru9uJKU9b4pjVy/zcUJSph0voIDkxU+OXofIC7xwixAnZw8AVoOcPp2/Mg908= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=S0SbH50b; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="S0SbH50b" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F31B5C116D0; Wed, 25 Feb 2026 06:56:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1772002587; bh=Nof224jaw1S8dxPoH/9AIp/MoIv5D48FJF+tPwUhdfg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=S0SbH50bOkPe5UA4CvQ6MGlCXoV7lHHh+p3cY6EamMOUL6soV7wvzPz6XXKtH9swQ Te1hm8Jzr97V2u9gXb7jVpluMul0KdmAlAYebUbTefg1/TO3yNXappxykaf6XDcehN bSXuiXSuhvyiDBhbzv9kwZnxIiGnNu9z4btNpgIM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jinliang Zheng , Oleg Nesterov , David Hildenbrand , Ingo Molnar , Lorenzo Stoakes , Mateusz Guzik , ruippan , Usama Arif , Andrew Morton , Sasha Levin Subject: [PATCH 6.18 324/641] procfs: fix missing RCU protection when reading real_parent in do_task_stat() Date: Tue, 24 Feb 2026 17:20:50 -0800 Message-ID: <20260225012356.553191674@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260225012348.915798704@linuxfoundation.org> References: <20260225012348.915798704@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ 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 2ae63189091e0..038d4b57127fe 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -529,7 +529,7 @@ 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