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 07AD617C995; Thu, 15 Aug 2024 14:43:35 +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=1723733015; cv=none; b=FF/BQLlXxFfXjqG8gAWJLu9vQW3PQQR+AEIPkqZt3TpUa95RUHZd3yCIg10n6Tm7cpUxPpnWMqv2JU5Zz9aEjXkWC9XlN/y7wPK838BX01OYXGnvYfsRA68POE46QM2olfB43akWrtLqyJGIDDug88g2VuFAoAatcwn8Kg2htjU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723733015; c=relaxed/simple; bh=GFde3IDjYJ7KwEuM9LyY8JLGav+Hx2cKw8f/V4fVptA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=EfjXaiKl0XZiB/LAyrdhFYr0qlNzWdsIdRexz9I9QOzfw2dPxSmES6I79AKl2ze/5V1B1ZHGFIMIjDsAdRBhgvO9pmdzzakv4R2DOkHlQD64Ksa1xvXt4OG008GS/0yAQWG6IrBY6sL29I2ueukypUJm/wk86UMrIbisp9LNiaw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=0WnhD5yL; 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="0WnhD5yL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6AAD6C32786; Thu, 15 Aug 2024 14:43:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1723733014; bh=GFde3IDjYJ7KwEuM9LyY8JLGav+Hx2cKw8f/V4fVptA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0WnhD5yLEA+YH8sWj5M5+T6tJGTD+tPmwVRPRi2kN5/e9zkPYuSpdHv0IfjKdbYm/ BbF7miIu3+MvoiEdFv9zbiYoVHTY5EGklDB1PWm8j0hpFZ3EWAo8oRLCND6aNlOT90 DZmm/TC/22oMpVd9H9fapXOoOSQ9DnVdBzgckoLk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Waiman Long , Daniel Jordan , Steffen Klassert , Andrew Morton Subject: [PATCH 5.10 324/352] padata: Fix possible divide-by-0 panic in padata_mt_helper() Date: Thu, 15 Aug 2024 15:26:30 +0200 Message-ID: <20240815131931.976294445@linuxfoundation.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240815131919.196120297@linuxfoundation.org> References: <20240815131919.196120297@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Waiman Long commit 6d45e1c948a8b7ed6ceddb14319af69424db730c upstream. We are hit with a not easily reproducible divide-by-0 panic in padata.c at bootup time. [ 10.017908] Oops: divide error: 0000 1 PREEMPT SMP NOPTI [ 10.017908] CPU: 26 PID: 2627 Comm: kworker/u1666:1 Not tainted 6.10.0-15.el10.x86_64 #1 [ 10.017908] Hardware name: Lenovo ThinkSystem SR950 [7X12CTO1WW]/[7X12CTO1WW], BIOS [PSE140J-2.30] 07/20/2021 [ 10.017908] Workqueue: events_unbound padata_mt_helper [ 10.017908] RIP: 0010:padata_mt_helper+0x39/0xb0 : [ 10.017963] Call Trace: [ 10.017968] [ 10.018004] ? padata_mt_helper+0x39/0xb0 [ 10.018084] process_one_work+0x174/0x330 [ 10.018093] worker_thread+0x266/0x3a0 [ 10.018111] kthread+0xcf/0x100 [ 10.018124] ret_from_fork+0x31/0x50 [ 10.018138] ret_from_fork_asm+0x1a/0x30 [ 10.018147] Looking at the padata_mt_helper() function, the only way a divide-by-0 panic can happen is when ps->chunk_size is 0. The way that chunk_size is initialized in padata_do_multithreaded(), chunk_size can be 0 when the min_chunk in the passed-in padata_mt_job structure is 0. Fix this divide-by-0 panic by making sure that chunk_size will be at least 1 no matter what the input parameters are. Link: https://lkml.kernel.org/r/20240806174647.1050398-1-longman@redhat.com Fixes: 004ed42638f4 ("padata: add basic support for multithreaded jobs") Signed-off-by: Waiman Long Cc: Daniel Jordan Cc: Steffen Klassert Cc: Waiman Long Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- kernel/padata.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/kernel/padata.c +++ b/kernel/padata.c @@ -521,6 +521,13 @@ void __init padata_do_multithreaded(stru ps.chunk_size = max(ps.chunk_size, job->min_chunk); ps.chunk_size = roundup(ps.chunk_size, job->align); + /* + * chunk_size can be 0 if the caller sets min_chunk to 0. So force it + * to at least 1 to prevent divide-by-0 panic in padata_mt_helper().` + */ + if (!ps.chunk_size) + ps.chunk_size = 1U; + list_for_each_entry(pw, &works, pw_list) queue_work(system_unbound_wq, &pw->pw_work);