Linux Media Controller development
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From: Sergey Nalivayko <Sergey.Nalivayko@kaspersky.com>
To: Wolfram Sang <wsa+renesas@sang-engineering.com>,
	Alan Stern <stern@rowland.harvard.edu>
Cc: "linux-media@vger.kernel.org" <linux-media@vger.kernel.org>,
	"Mauro Carvalho Chehab" <mchehab@kernel.org>,
	Antoine Jacquet <royale@zerezo.com>,
	Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
	"lvc-project@linuxtesting.org" <lvc-project@linuxtesting.org>,
	"syzbot+0335df380edd9bd3ff70@syzkaller.appspotmail.com"
	<syzbot+0335df380edd9bd3ff70@syzkaller.appspotmail.com>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>
Subject: RE: [PATCH] dvb-usb: dtv5100: rewrite i2c message usb_control send/recv
Date: Fri, 21 Nov 2025 13:07:32 +0000	[thread overview]
Message-ID: <f2e6bea0262748bc9c6fdcf81cd70607@kaspersky.com> (raw)
In-Reply-To: <aR4dFL75cdb0ccQQ@shikoro>

>On Wed, Nov 19, 2025 at 18:51, Alan Stern wrote:
>> Can't this problem be fixed more simply by setting the 
>> I2C_AQ_NO_ZERO_LEN_READ adapter quirk flag, as in some of Wolfram 
>> Sang's recent commits?

On Wed, Nov 19, 2025 at 22:40, Wolfram Sang wrote:
> I think so. Hmm, I searched the tree for potential candidates. Seems this slipped through :( For reference, I fixed it in another media driver with commit b5ae5a79825b ("media: usb: hdpvr: disable zero-length read messages").

Thanks for your comment. Unfortunately, setting the I2C_AQ_NO_ZERO_LEN_READ adapter quirk does not solve the issue, as the problem occurs within the dtv5100_i2c_msg() function itself when it receives a message of NON-ZERO length. A message with length 1 arrives,  but it's expected only in the case of a combined write/read operation,  when two messages arrive simultaneously via the I2C interface (this is explicitly checked in the condition). If there's only one message, the  last parameter of the dtv5100_i2c_msg() function, rlen, is 0,  and a parameter inconsistency error occurs.

      reply	other threads:[~2025-11-21 13:07 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-11-17 15:53 [PATCH] dvb-usb: dtv5100: rewrite i2c message usb_control send/recv Nalivayko Sergey
2025-11-19 15:51 ` Alan Stern
2025-11-19 19:40   ` Wolfram Sang
2025-11-21 13:07     ` Sergey Nalivayko [this message]

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