Re: [PATCH net] can: peak_usb: accept short uCAN end-of-list records

["Stéphane Grosjean" <stephane.grosjean@free.fr>]

Hi Marc,

On 19.10.2026 00:46:34, Liu Changjie wrote:
> A PCAN-USB FD v2 running firmware 3.2.0 sends a 16-byte status
> record followed by a four-byte zero-size end marker. These transfers
> cause repeated receive-buffer dumps while the interface is up.
>
> pcan_usb_fd_decode_buf() requires a complete 12-byte struct pucan_msg
> before checking the size field, so it rejects the end marker with
> -EBADMSG.

Right: the firmware may terminate a list of records with a short null
record, and it doesn't need to be a full struct pucan_msg. Only its size
field matters.

The patch keeps all the record length checks added by 93fcab2c6968 and
only accepts the end marker earlier, so:

Reviewed-by: Stéphane Grosjean <s.grosjean@peak-system.fr>

Marc, since 93fcab2c6968 has been backported to the 6.6, 6.12 and 7.1
stable trees, could you add "Cc: stable@vger.kernel.org" when applying?

Thanks,

Stéphane

----- Mail original -----
> Stéphane,
> 
> can you have a look at this?
> 
> On 19.10.2026 00:46:34, Liu Changjie wrote:
> > A PCAN-USB FD v2 running firmware 3.2.0 sends a 16-byte status
> > record followed by a four-byte zero-size end marker. These
> > transfers
> > cause repeated receive-buffer dumps while the interface is up.
> >
> > pcan_usb_fd_decode_buf() requires a complete 12-byte struct
> > pucan_msg
> > before checking the size field, so it rejects the end marker with
> > -EBADMSG.
> >
> > Check that the size field is present before testing for an end
> > marker.
> > Require the full header for nonzero-size records and keep the
> > remaining
> > record and payload length checks.
> >
> > Fixes: 93fcab2c6968 ("can: peak_usb: validate uCAN receive record
> > lengths")
> > Assisted-by: LLM
> > Signed-off-by: Liu Changjie <liucj1228@outlook.com>
> 
> Marc
> 
> --
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