[Salvatore Bonaccorso <carnil@debian.org>]

Bcc: 
Subject: Re: [RFC] usb: typec: ucsi: Fix array index out-of-bounds in altmode
 registration
Reply-To: 
In-Reply-To: <2026011617-phantom-diploma-cd79@gregkh>

Hi Greg, hi Heikki

On Fri, Jan 16, 2026 at 12:22:42PM +0100, Greg KH wrote:
> On Thu, Jan 15, 2026 at 11:32:01AM +0800, xiaopeitux@foxmail.com wrote:
> > From: Pei Xiao <xiaopei01@kylinos.cn>
> > 
> > Add boundary check to prevent array index out-of-bounds when PPM returns
> > more alternate modes than expected.
> > 
> > log:
> > UBSAN: array-index-out-of-bounds in /build/reproducible-path/linux-6.17.13/drivers/usb/typec/ucsi/ucsi.c:609:18
> > index 2 is out of range for type 'ucsi_altmode [2]'
> > CPU: 10 UID: 0 PID: 275 Comm: kworker/10:1 Not tainted 6.17.13+deb14-amd64 #1 PREEMPT(lazy)  Debian 6.17.13-1
> > Hardware name: LENOVO 83J3/LNVNB161216, BIOS PYCN30WW 11/17/2025
> > Workqueue: events_long ucsi_init_work [typec_ucsi]
> > Call Trace:
> > <TASK>
> > dump_stack_lvl+0x5d/0x80
> > ubsan_epilogue+0x5/0x2b
> > __ubsan_handle_out_of_bounds.cold+0x54/0x59
> > ucsi_register_altmodes+0x233/0x250 [typec_ucsi]
> > ucsi_check_altmodes+0x1b/0xa0 [typec_ucsi]
> > ucsi_init_work+0x919/0x9b0 [typec_ucsi]
> > process_one_work+0x192/0x350
> > worker_thread+0x25a/0x3a0
> > 
> > Reported-by: Salvatore Bonaccorso <carnil@debian.org>
> > Closes: https://lore.kernel.org/lkml/176840984804.2144647.10736984532804520381@eldamar.lan
> > Signed-off-by: Pei Xiao <xiaopei01@kylinos.cn>
> > ---
> >  drivers/usb/typec/ucsi/ucsi.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
> > index a7b388dc7fa0..00575a8720cc 100644
> > --- a/drivers/usb/typec/ucsi/ucsi.c
> > +++ b/drivers/usb/typec/ucsi/ucsi.c
> > @@ -599,6 +599,8 @@ static int ucsi_register_altmodes(struct ucsi_connector *con, u8 recipient)
> >  		 * incremented.
> >  		 */
> >  		num = len / sizeof(alt[0]);
> > +		if (num > ARRAY_SIZE(alt))
> > +			num = ARRAY_SIZE(alt);
> 
> As Heikki said, this is a broken hardware device, please fix that
> instead as it will not work with any other operating system either :)

Thanks a lot for looking into it. Pascal, can you pleas report this
issue then to the vendor as it is a firmware bug?

Regards,
Salvatore