Re: [PATCH] drm: bridge: sii8620: fix possible off-by-one

From: Hangyu Hua <hbh25y@gmail.com>
To: Andrzej Hajda <andrzej.hajda@intel.com>,
	narmstrong@baylibre.com, robert.foss@linaro.org,
	Laurent.pinchart@ideasonboard.com, jonas@kwiboo.se,
	jernej.skrabec@gmail.com, airlied@linux.ie, daniel@ffwll.ch,
	architt@codeaurora.org
Cc: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH] drm: bridge: sii8620: fix possible off-by-one
Date: Thu, 23 Jun 2022 10:55:01 +0800	[thread overview]
Message-ID: <fe6fe929-578e-5828-7886-3fe69b9d3a6a@gmail.com> (raw)
In-Reply-To: <dc52f807-f4bc-13d6-7b9e-81b4fe94a6e0@intel.com>

On 2022/5/18 15:57, Andrzej Hajda wrote:
> 
> 
> On 18.05.2022 08:58, Hangyu Hua wrote:
>> The next call to sii8620_burst_get_tx_buf will result in off-by-one
>> When ctx->burst.tx_count + size == ARRAY_SIZE(ctx->burst.tx_buf). The 
>> same
>> thing happens in sii8620_burst_get_rx_buf.
>>
>> This patch also change tx_count and tx_buf to rx_count and rx_buf in
>> sii8620_burst_get_rx_buf. It is unreasonable to check tx_buf's size and
>> use rx_buf.
>>
>> Fixes: e19e9c692f81 ("drm/bridge/sii8620: add support for burst eMSC 
>> transmissions")
>> Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
> Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
> 
> Regards
> Andrzej
>> ---
>>   drivers/gpu/drm/bridge/sil-sii8620.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/bridge/sil-sii8620.c 
>> b/drivers/gpu/drm/bridge/sil-sii8620.c
>> index ec7745c31da0..ab0bce4a988c 100644
>> --- a/drivers/gpu/drm/bridge/sil-sii8620.c
>> +++ b/drivers/gpu/drm/bridge/sil-sii8620.c
>> @@ -605,7 +605,7 @@ static void *sii8620_burst_get_tx_buf(struct 
>> sii8620 *ctx, int len)
>>       u8 *buf = &ctx->burst.tx_buf[ctx->burst.tx_count];
>>       int size = len + 2;
>> -    if (ctx->burst.tx_count + size > ARRAY_SIZE(ctx->burst.tx_buf)) {
>> +    if (ctx->burst.tx_count + size >= ARRAY_SIZE(ctx->burst.tx_buf)) {
>>           dev_err(ctx->dev, "TX-BLK buffer exhausted\n");
>>           ctx->error = -EINVAL;
>>           return NULL;
>> @@ -622,7 +622,7 @@ static u8 *sii8620_burst_get_rx_buf(struct sii8620 
>> *ctx, int len)
>>       u8 *buf = &ctx->burst.rx_buf[ctx->burst.rx_count];
>>       int size = len + 1;
>> -    if (ctx->burst.tx_count + size > ARRAY_SIZE(ctx->burst.tx_buf)) {
>> +    if (ctx->burst.rx_count + size >= ARRAY_SIZE(ctx->burst.rx_buf)) {
>>           dev_err(ctx->dev, "RX-BLK buffer exhausted\n");
>>           ctx->error = -EINVAL;
>>           return NULL;
> 

Hi guys,

Another patches for this module that I submitted at the same time as
this one have been merged. Is this patch forgotten to merge?

Thanks,
Hangyu