From: Wolfram Sang <wsa+renesas@sang-engineering.com>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>,
syzbot <syzbot+c38e5e60d0041a99dbf5@syzkaller.appspotmail.com>,
gregkh@linuxfoundation.org, linux-i2c@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org,
syzkaller-bugs@googlegroups.com
Subject: Re: [PATCH v2 resend] media: dvb: usb: Fix WARNING in dib0700_i2c_xfer/usb_submit_urb
Date: Sat, 29 Mar 2025 07:05:49 +0100 [thread overview]
Message-ID: <Z-eNvcrFu0VSY23U@shikoro> (raw)
In-Reply-To: <24798648-c5a3-4e31-9897-4610053007f3@rowland.harvard.edu>
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> In the case of dib0700, it was clear from the source code that the
> driver uses USB Control transfers to tell the hardware about I2C
> messages. I don't know if other bridges work in the same way. In
> theory a bridge could use USB Bulk transfers instead; they aren't
> subject to this restriction on length-0 reads. Or a bridge could use a
> Control read transfer but include extra header material along with the
> actual data, so that a length-0 message wouldn't end up generating a
> length-0 read.
Fully understood, thanks for your explanation.
> So the short answer is that you would need to find someone who really
> understands what's going on here -- which I don't. Sorry.
No worries. There are only 5 drivers or so, I will manually check if
they use a control_read and have no own header. Doesn't sound hard.
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next prev parent reply other threads:[~2025-03-29 6:05 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-24 18:18 [syzbot] [usb?] WARNING in dib0700_i2c_xfer/usb_submit_urb syzbot
2025-03-24 19:08 ` Alan Stern
2025-03-24 19:19 ` Wolfram Sang
2025-03-25 16:41 ` Alan Stern
2025-03-25 16:59 ` Wolfram Sang
2025-03-25 17:47 ` Alan Stern
2025-03-25 19:07 ` syzbot
2025-03-25 19:28 ` [PATCH] media: dvb: usb: Fix " Alan Stern
2025-03-25 19:56 ` Wolfram Sang
2025-03-25 21:47 ` Alan Stern
2025-03-25 22:17 ` Wolfram Sang
2025-03-26 15:28 ` [PATCH v2] " Alan Stern
2025-03-26 15:54 ` Wolfram Sang
2025-03-26 16:04 ` Alan Stern
2025-03-26 21:32 ` Wolfram Sang
2025-03-27 16:10 ` [PATCH v2 resend] " Alan Stern
2025-03-28 15:45 ` Wolfram Sang
2025-03-29 2:08 ` Alan Stern
2025-03-29 6:05 ` Wolfram Sang [this message]
2025-03-29 14:31 ` Alan Stern
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