From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-172.mta0.migadu.com (out-172.mta0.migadu.com [91.218.175.172]) (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 67296433CB for ; Mon, 14 Apr 2025 13:01:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744635702; cv=none; b=hqVr/SV05ECqsgf92QLOEChJ253Oa4oB0DTmGqgy9vIQm4IscykAd27/8SzCv4QpbeJwpXx05gChhFK9ihdCKxU/sDc7nYo3X2BFQFRKusoQfngsvmsK9aFB+2aPIxkNOYCJ9XFKdwzmGvPGhY7bzFndzttcPRS/vVMaV7iymls= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744635702; c=relaxed/simple; bh=cQpYBJT1BS6d2aNLlx3jhhLQ73c+7Qwy83avSo07Uaw=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=HlAGZrO4mGw8vCAkX3l5CyvXV48mMUOz2NZGqMkAMfE/Lq6B/iUN+fZ9YvIjXzC7l3vmCgfArGEkg9eTzKOpjya6i1IebTsdAuu+BQH6K49vwotPz1KBOu+6S0xa+DaygO+9J5KbHbx8tJ+Sb1EutpbXmkiCVMD0RYTfTi1zqG8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=CZLYlnOY; arc=none smtp.client-ip=91.218.175.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="CZLYlnOY" Message-ID: <39839bcb-90e9-4886-913d-311c75c92ad8@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1744635698; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=92Ns63mKqKSi1Gpjb4z8VtgowBHrPaaCCaojmxVMIOU=; b=CZLYlnOYrK7MvKRVU8lfgTrDdE9WR+TaY23koug0t86L9mHPPxPReugOzKI/avqRADBrEP l1rh9yUYnwwH6MUjUlkwEIVzw/MtG/qio10CHcHluDYUrWOa8I5EeitQgXkwqiFc09hZbI pWiu0eZ2YwR7/QeNH7Rxvfdf4WWyjKs= Date: Mon, 14 Apr 2025 14:01:35 +0100 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH v1] ptp: ocp: fix NULL deref in _signal_summary_show To: Sagi Maimon Cc: jonathan.lemon@gmail.com, richardcochran@gmail.com, andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org References: <20250414085412.117120-1-maimon.sagi@gmail.com> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Vadim Fedorenko In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On 14/04/2025 12:38, Sagi Maimon wrote: > On Mon, Apr 14, 2025 at 2:09 PM Vadim Fedorenko > wrote: >> >> On 14/04/2025 11:56, Sagi Maimon wrote: >>> On Mon, Apr 14, 2025 at 12:37 PM Vadim Fedorenko >>> wrote: >>>> >>>> On 14/04/2025 09:54, Sagi Maimon wrote: >>>>> Sysfs signal show operations can invoke _signal_summary_show before >>>>> signal_out array elements are initialized, causing a NULL pointer >>>>> dereference. Add NULL checks for signal_out elements to prevent kernel >>>>> crashes. >>>>> >>>>> Fixes: b325af3cfab9 ("ptp: ocp: Add signal generators and update sysfs nodes") >>>>> Signed-off-by: Sagi Maimon >>>>> --- >>>>> drivers/ptp/ptp_ocp.c | 3 +++ >>>>> 1 file changed, 3 insertions(+) >>>>> >>>>> diff --git a/drivers/ptp/ptp_ocp.c b/drivers/ptp/ptp_ocp.c >>>>> index 7945c6be1f7c..4c7893539cec 100644 >>>>> --- a/drivers/ptp/ptp_ocp.c >>>>> +++ b/drivers/ptp/ptp_ocp.c >>>>> @@ -3963,6 +3963,9 @@ _signal_summary_show(struct seq_file *s, struct ptp_ocp *bp, int nr) >>>>> bool on; >>>>> u32 val; >>>>> >>>>> + if (!bp->signal_out[nr]) >>>>> + return; >>>>> + >>>>> on = signal->running; >>>>> sprintf(label, "GEN%d", nr + 1); >>>>> seq_printf(s, "%7s: %s, period:%llu duty:%d%% phase:%llu pol:%d", >>>> >>>> That's not correct, the dereference of bp->signal_out[nr] happens before >>>> the check. But I just wonder how can that even happen? >>>> >>> The scenario (our case): on ptp_ocp_adva_board_init we >>> initiate only signals 0 and 1 so 2 and 3 are NULL. >>> Later ptp_ocp_summary_show runs on all 4 signals and calls _signal_summary_show >>> when calling signal 2 or 3 the dereference occurs. >>> can you please explain: " the dereference of bp->signal_out[nr] happens before >>> the check", where exactly? do you mean in those lines: >>> struct signal_reg __iomem *reg = bp->signal_out[nr]->mem; >> ^^^ >> yes, this is the line which dereferences the pointer. >> >> but in case you have only 2 pins to configure, why the driver exposes 4 >> SMAs? You can simply adjust the attributes (adva_timecard_attrs). >> > I can (and will) expose only 2 sma in adva_timecard_attrs, but still > ptp_ocp_summary_show runs > on all 4 signals and not only on the on that exposed, is it not a bug? Yeah, it's a bug, but different one, and we have to fix it other way. >>> struct ptp_ocp_signal *signal = &bp->signal[nr]; >>>> I believe the proper fix is to move ptp_ocp_attr_group_add() closer to >>>> the end of ptp_ocp_adva_board_init() like it's done for other boards. >>>> >>>> -- >>>> pw-bot: cr >>