From: Juan Perdomo <jcperdomo100@gmail.com>
To: mchehab@kernel.org
Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
syzbot+ddccc0c0dbc0a38ffccb@syzkaller.appspotmail.com
Subject: [PATCH] media: cx231xx: preserve I2C transfer length
Date: Tue, 8 Sep 2026 00:07:34 -0400 [thread overview]
Message-ID: <20260908040734.1175-1-jcperdomo100@gmail.com> (raw)
The I2C core stores message lengths in u16, but cx231xx truncates them to
u8 when populating cx231xx_i2c_xfer_data. A 0x700-byte read therefore
becomes a zero-length request. USB treats zero-length control transfers as
OUT regardless of bRequestType, so the IN control pipe trips the
usb_submit_urb() direction warning.
Use u16 for buf_size, matching both i2c_msg.len and
VENDOR_REQUEST_IN.wLength. Oversized transfers then reach the existing
URB_MAX_CTRL_SIZE check and return -EINVAL.
Fixes: e0d3bafd0258 ("V4L/DVB (10954): Add cx231xx USB driver")
Reported-by: syzbot+ddccc0c0dbc0a38ffccb@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=ddccc0c0dbc0a38ffccb
Tested-by: syzbot+ddccc0c0dbc0a38ffccb@syzkaller.appspotmail.com
Signed-off-by: Juan Perdomo <jcperdomo100@gmail.com>
---
Testing:
- Syzbot reproduced the original USB direction warning on unpatched
df290809 (Linux 7.3-rc2).
https://syzkaller.appspot.com/x/report.txt?x=1107e749580000
- Built the complete cx231xx linked object on ARM64 with GCC 11.4.0,
CONFIG_VIDEO_CX231XX=m and W=1.
- Syzbot tested the patch on df290809 (Linux 7.3-rc2) with Clang 22.1.8;
the supplied reproducer did not trigger an issue.
https://syzkaller.appspot.com/x/log.txt?x=1123f105580000
No physical-device testing was performed.
drivers/media/usb/cx231xx/cx231xx.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/media/usb/cx231xx/cx231xx.h b/drivers/media/usb/cx231xx/cx231xx.h
index 19f5036a7..f85d054fb 100644
--- a/drivers/media/usb/cx231xx/cx231xx.h
+++ b/drivers/media/usb/cx231xx/cx231xx.h
@@ -463,7 +463,7 @@ struct cx231xx_i2c_xfer_data {
u8 direction; /* 1 - IN, 0 - OUT */
u8 saddr_len; /* sub address len */
u16 saddr_dat; /* sub addr data */
- u8 buf_size; /* buffer size */
+ u16 buf_size; /* buffer size */
u8 *p_buffer; /* pointer to the buffer */
};
base-commit: df2908090cda368b01ff43709f51890076c56157
--
2.50.1 (Apple Git-155)
reply other threads:[~2026-09-08 4:08 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260908040734.1175-1-jcperdomo100@gmail.com \
--to=jcperdomo100@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-media@vger.kernel.org \
--cc=mchehab@kernel.org \
--cc=syzbot+ddccc0c0dbc0a38ffccb@syzkaller.appspotmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®