Messages in this thread | | | Subject | Re: [RFC PATCH] usb: typec: tcpm: Ignore unsupported/unknown alternate mode requests | From | Douglas Gilbert <> | Date | Fri, 2 Aug 2019 17:25:17 +0200 |
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On 2019-07-25 6:30 a.m., Guenter Roeck wrote: > TCPM may receive PD messages associated with unknown or unsupported > alternate modes. If that happens, calls to typec_match_altmode() > will return NULL. The tcpm code does not currently take this into > account. This results in crashes. > > Unable to handle kernel NULL pointer dereference at virtual address 000001f0 > pgd = 41dad9a1 > [000001f0] *pgd=00000000 > Internal error: Oops: 5 [#1] THUMB2 > Modules linked in: tcpci tcpm > CPU: 0 PID: 2338 Comm: kworker/u2:0 Not tainted 5.1.18-sama5-armv7-r2 #6 > Hardware name: Atmel SAMA5 > Workqueue: 2-0050 tcpm_pd_rx_handler [tcpm] > PC is at typec_altmode_attention+0x0/0x14 > LR is at tcpm_pd_rx_handler+0xa3b/0xda0 [tcpm] > ... > [<c03fbee8>] (typec_altmode_attention) from [<bf8030fb>] > (tcpm_pd_rx_handler+0xa3b/0xda0 [tcpm]) > [<bf8030fb>] (tcpm_pd_rx_handler [tcpm]) from [<c012082b>] > (process_one_work+0x123/0x2a8) > [<c012082b>] (process_one_work) from [<c0120a6d>] > (worker_thread+0xbd/0x3b0) > [<c0120a6d>] (worker_thread) from [<c012431f>] (kthread+0xcf/0xf4) > [<c012431f>] (kthread) from [<c01010f9>] (ret_from_fork+0x11/0x38) > > Ignore PD messages if the asociated alternate mode is not supported. > > Reported-by: Douglas Gilbert <dgilbert@interlog.com> > Cc: Douglas Gilbert <dgilbert@interlog.com> > Fixes: e9576fe8e605c ("usb: typec: tcpm: Support for Alternate Modes") > Signed-off-by: Guenter Roeck <linux@roeck-us.net> > --- > Taking a stab at the problem. I don't really know if this is the correct > fix, or even if my understanding of the problem is correct, thus marking > the patch as RFC.
Tested-by: Douglas Gilbert <dgilbert@interlog.com>
Tested on different hardware (Acme Arietta based on at91sam9g25) and lk 5.2.5 . Without this patch the oops was at PC is at typec_altmode_attention+0x0/0x24 [typec]
The DUT was a Arietta with a OM13588 attached acting as a PD sink. At the other end of the type C cable was a KL27Z+OM13588 running NXP's usb_pd_bm app and it was a PD source. The other end did a "send attention" to cause the oops.
With this patch nothing happened. Notable there was no oops. The other end (KL27Z+OM13588 reported "send attention result: success" but it also did that in the previous "oops" case.
Is there something to replace "tail -f" that would make it easier to monitor what is being sent to /sys/kernel/debug/tcpm/1-0050 ?
Doug Gilbert
> drivers/usb/typec/tcpm/tcpm.c | 38 ++++++++++++++++++++++++-------------- > 1 file changed, 24 insertions(+), 14 deletions(-) > > diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c > index 77f71f602f73..1df2844469aa 100644 > --- a/drivers/usb/typec/tcpm/tcpm.c > +++ b/drivers/usb/typec/tcpm/tcpm.c > @@ -1096,7 +1096,8 @@ static int tcpm_pd_svdm(struct tcpm_port *port, const __le32 *payload, int cnt, > break; > case CMD_ATTENTION: > /* Attention command does not have response */ > - typec_altmode_attention(adev, p[1]); > + if (adev) > + typec_altmode_attention(adev, p[1]); > return 0; > default: > break; > @@ -1148,20 +1149,26 @@ static int tcpm_pd_svdm(struct tcpm_port *port, const __le32 *payload, int cnt, > } > break; > case CMD_ENTER_MODE: > - typec_altmode_update_active(pdev, true); > - > - if (typec_altmode_vdm(adev, p[0], &p[1], cnt)) { > - response[0] = VDO(adev->svid, 1, CMD_EXIT_MODE); > - response[0] |= VDO_OPOS(adev->mode); > - return 1; > + if (adev && pdev) { > + typec_altmode_update_active(pdev, true); > + > + if (typec_altmode_vdm(adev, p[0], &p[1], cnt)) { > + response[0] = VDO(adev->svid, 1, > + CMD_EXIT_MODE); > + response[0] |= VDO_OPOS(adev->mode); > + return 1; > + } > } > return 0; > case CMD_EXIT_MODE: > - typec_altmode_update_active(pdev, false); > + if (adev && pdev) { > + typec_altmode_update_active(pdev, false); > > - /* Back to USB Operation */ > - WARN_ON(typec_altmode_notify(adev, TYPEC_STATE_USB, > - NULL)); > + /* Back to USB Operation */ > + WARN_ON(typec_altmode_notify(adev, > + TYPEC_STATE_USB, > + NULL)); > + } > break; > default: > break; > @@ -1171,8 +1178,10 @@ static int tcpm_pd_svdm(struct tcpm_port *port, const __le32 *payload, int cnt, > switch (cmd) { > case CMD_ENTER_MODE: > /* Back to USB Operation */ > - WARN_ON(typec_altmode_notify(adev, TYPEC_STATE_USB, > - NULL)); > + if (adev) > + WARN_ON(typec_altmode_notify(adev, > + TYPEC_STATE_USB, > + NULL)); > break; > default: > break; > @@ -1183,7 +1192,8 @@ static int tcpm_pd_svdm(struct tcpm_port *port, const __le32 *payload, int cnt, > } > > /* Informing the alternate mode drivers about everything */ > - typec_altmode_vdm(adev, p[0], &p[1], cnt); > + if (adev) > + typec_altmode_vdm(adev, p[0], &p[1], cnt); > > return rlen; > } >
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