On 7/30/19 5:07 AM, Heikki Krogerus wrote:
On Mon, Jul 29, 2019 at 10:31:04AM -0700, Guenter Roeck wrote:
On Mon, Jul 29, 2019 at 05:04:57PM +0300, Heikki Krogerus wrote:
Hi,
On Wed, Jul 24, 2019 at 09:30:37PM -0700, 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@xxxxxxxxxxxx>
Cc: Douglas Gilbert <dgilbert@xxxxxxxxxxxx>
Fixes: e9576fe8e605c ("usb: typec: tcpm: Support for Alternate Modes")
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
---
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.
My guess is that typec_match_altmode() is the real culprit. We can't
rely on the partner mode index number when identifying the port alt
mode.
Douglas, can you test the attached hack instead of this patch?
thanks,
--
heikki
diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index ec525811a9eb..033dc097ba83 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -1067,12 +1067,11 @@ static int tcpm_pd_svdm(struct tcpm_port *port, const __le32 *payload, int cnt,
modep = &port->mode_data;
- adev = typec_match_altmode(port->port_altmode, ALTMODE_DISCOVERY_MAX,
- PD_VDO_VID(p[0]), PD_VDO_OPOS(p[0]));
-
pdev = typec_match_altmode(port->partner_altmode, ALTMODE_DISCOVERY_MAX,
PD_VDO_VID(p[0]), PD_VDO_OPOS(p[0]));
+ adev = (void *)typec_altmode_get_partner(pdev);
+
I understand that typec_altmode_get_partner() returns a const *;
maybe adev should be declared as const struct typec_altmode *
instead of using a typecast.
Yes...
Also, typec_altmode_get_partner() can return NULL as well if pdev is NULL.
Is it guaranteed that typec_match_altmode() never returns NULL for pdev ?
...and probable no. But I don't think we can receive Attention to a
mode that hasn't been entered.
If I understand correctly, the Attention was generated by a test system.
What prevents badly implemented code in the connected system from sending
such an Attention message ?
Thanks,
Guenter
