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 7E13329CA; Mon, 12 Aug 2024 16:20:44 +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=1723479644; cv=none; b=vDXUSNgMrNsSBw2StUEcb6Tnzv99gFcgGT7y32bDmFO76XGy4NLTq5hXQiRos/gNeSHI66c5NzTjDU4HhR8flpS41AS9q5n9P0QNvslYF63ejPP3zqGvGIrMSQAXYQqIjiZ1Cv/aybHuDcNMmBqzpjxrFhQBLVnmv3H59kzrGPY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723479644; c=relaxed/simple; bh=lYXC+0wJdcwRMYhLqob9gnem2CiguNZqBEUWhTeDuIc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=kFtzJZN5rLzh3hSicR9CctFzjolwzDQsFNGJMwHrMmxjFxLRissAAxBu9JsAPzH2N/sKgEhIEOgOEvRPV/MoMWQMuOxp+u22K7T6CbAHSb77Ns3Uzgj/UeDRRNZktx38RtEjTp75I+xoF3TG6+mbJXT1yvQm+ozUYjITEPsJQlc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=D5jnI0zq; 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="D5jnI0zq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E1421C32782; Mon, 12 Aug 2024 16:20:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1723479644; bh=lYXC+0wJdcwRMYhLqob9gnem2CiguNZqBEUWhTeDuIc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=D5jnI0zqP49AaCrY5X/upG8K3gKnc4DGkN5e6wQZHYdz4poehOAgU9RBkWPwqk/Gw RuoAxDKEiziuwjrYg+coBgzTomeYxvfNJVS8GwKFRCyHeYoH04pqrUYPGh0dq74ubg TLrKsR9d6EqFrR68RY22yFW4+QFOfnGAm3mEq6uo= 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 6.6 149/189] padata: Fix possible divide-by-0 panic in padata_mt_helper() Date: Mon, 12 Aug 2024 18:03:25 +0200 Message-ID: <20240812160137.878226473@linuxfoundation.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240812160132.135168257@linuxfoundation.org> References: <20240812160132.135168257@linuxfoundation.org> User-Agent: quilt/0.67 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 6.6-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 @@ -516,6 +516,13 @@ 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);