linux-kernel - Re: [PATCH 1/3] net: ethernet: bcmasp: fix possible OOB write in bcmasp_netfilt_get_all

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Message-ID: <94d077db-01e3-404e-1027-fb7532dc3c5c@gmail.com>
Date:   Fri, 8 Sep 2023 10:59:12 +0800
From:   Hangyu Hua <hbh25y@...il.com>
To:     Paolo Abeni <pabeni@...hat.com>, justin.chen@...adcom.com,
        florian.fainelli@...adcom.com, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, mw@...ihalf.com,
        linux@...linux.org.uk, nbd@....name, john@...ozen.org,
        sean.wang@...iatek.com, Mark-MC.Lee@...iatek.com,
        lorenzo@...nel.org, matthias.bgg@...il.com,
        angelogioacchino.delregno@...labora.com,
        maxime.chevallier@...tlin.com, nelson.chang@...iatek.com
Cc:     bcm-kernel-feedback-list@...adcom.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH 1/3] net: ethernet: bcmasp: fix possible OOB write in
 bcmasp_netfilt_get_all_active()

On 7/9/2023 17:44, Paolo Abeni wrote:
> On Wed, 2023-09-06 at 17:21 +0800, Hangyu Hua wrote:
>> rule_locs is allocated in ethtool_get_rxnfc and the size is determined by
>> rule_cnt from user space. So rule_cnt needs to be check before using
>> rule_locs to avoid OOB writing or NULL pointer dereference.
>>
>> Fixes: c5d511c49587 ("net: bcmasp: Add support for wake on net filters")
>> Signed-off-by: Hangyu Hua <hbh25y@...il.com>
>> ---
>>   drivers/net/ethernet/broadcom/asp2/bcmasp.c | 3 +++
>>   1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/net/ethernet/broadcom/asp2/bcmasp.c b/drivers/net/ethernet/broadcom/asp2/bcmasp.c
>> index d63d321f3e7b..4df2ca871af8 100644
>> --- a/drivers/net/ethernet/broadcom/asp2/bcmasp.c
>> +++ b/drivers/net/ethernet/broadcom/asp2/bcmasp.c
>> @@ -535,6 +535,9 @@ void bcmasp_netfilt_get_all_active(struct bcmasp_intf *intf, u32 *rule_locs,
>>   	int j = 0, i;
>>   
>>   	for (i = 0; i < NUM_NET_FILTERS; i++) {
>> +		if (j == *rule_cnt)
>> +			break;
> 
> Side note: it's a bit unfortunate/confusing that the drivers can
> arbitrary return  -EMSGSIZE or silently truncate the list. I think it
> would be clearer if we could stick to single behavior - and I'll vote
> for -EMSGSIZE.

I see. I used break directly here beacause this function is defined as
void. But since you mentioned this I will fix this out.

Thanks,
Hangyu

> 
> Cheers,
> 
> Paolo
>