From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-183.mta1.migadu.com (out-183.mta1.migadu.com [95.215.58.183]) (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 86CDD1F2BB8 for ; Wed, 16 Apr 2025 14:45:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.183 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744814727; cv=none; b=RGDIm5r2rcovrn1d+DX3REsyHRuGHGZWVPW0JiXDyZpcJZEF2WdtsaasXgX/a65BHTxFGI6K4YXfRhALeaAcLPsBMAeTooIlqSxuiwwCBWOruXdCRNrjU6a6lOMKluDS+Xrv1WKWwipSwieSxgJjJu1P1K3BsDAEOEbKfxJatYI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744814727; c=relaxed/simple; bh=AeLQqC3vX9HTHgUv20ss7rdlMBXzVBXV7nleNxqH11Q=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=LfZ2dQ3QPOtvC+q4r0h/0zvki2OP3Ly743TPfrzTdQ+787HQXWRyUH2ASmX2EIsVA6tUsiuD8/IPvXJdF1MDeJtUcPxCKwrhfxoaikc/DIUpYLAWs5cdEtNDY/IyjibwC4N7j/RcZfILwL92J+77mhyHLnNDgbPK6B4Ghfj0b+w= 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=amv0mO7m; arc=none smtp.client-ip=95.215.58.183 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="amv0mO7m" Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1744814712; 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=PFPVQCglhZ98jAXl7RgPw5PgOsI9U57zfBeHJT8Bs3Y=; b=amv0mO7m1+UkcEv1qboZNMN40LyJrq744QcjNqaEktEl+1mPe04uhoEPACcqr/PN9W+laC 0/nZwp1RMeePZcpXprvHwys8fxHRjDu8yjxjOvTW6VZNBcfuszm0Bq2BR/+A+ucxlntenx F0V3kR8S65/0KOUEPLrtPg+KXoRMOvs= Date: Wed, 16 Apr 2025 15:45:06 +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> <39839bcb-90e9-4886-913d-311c75c92ad8@linux.dev> <44b67f86-ed27-49e8-9e15-917fa2b75a60@linux.dev> <507eb775-d7df-4dd2-a7d1-626d5a51c1de@linux.dev> 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 16/04/2025 14:59, Sagi Maimon wrote: > On Wed, Apr 16, 2025 at 1:35 PM Vadim Fedorenko > wrote: >> >> On 16/04/2025 07:33, Sagi Maimon wrote: >>> On Mon, Apr 14, 2025 at 4:55 PM Vadim Fedorenko >>> wrote: >>>> >>>> On 14/04/2025 14:43, Sagi Maimon wrote: >>>>> On Mon, Apr 14, 2025 at 4:01 PM Vadim Fedorenko >>>>> wrote: >>>>>> >>>>>> 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. >>>>>> >>>>> Do you want to instruct me how to fix it , or will you fix it? >>>> >>>> well, the original device structure was not designed to have the amount >>>> of SMAs less than 4. We have to introduce another field to store actual >>>> amount of SMAs to work with, and adjust the code to check the value. The >>>> best solution would be to keep maximum amount of 4 SMAs in the structure >>>> but create a helper which will init new field and will have >>>> BUILD_BUG_ON() to prevent having more SMAs than fixed size array for >>>> them. That will solve your problem, but I will need to check it on the >>>> HW we run. >>>> >>> just to be clear you will write the fix and test it on your HW, so you >>> don't want me to write the fix? >> >> Well, it would be great if you can write the code which will make SMA >> functions flexible to the amount of pin the HW has. All our HW has fixed >> amount of 4 pins that's why the driver was coded with constants. Now >> your hardware has slightly different amount of pins, so it needs >> adjustments to the driver to work properly. I just want to be sure that >> any adjustments will not break my HW - that's what I meant saying I'll >> test it. >> > Just to be clear (correct me please if I am wrong): > I will write the code, then create a patch and upstream to the vanilla > you will test my change on your HW and only then approve the patch Yes, that's correct >>>>>>>>> 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 >>>>>>>> >>>>>> >>>> >>