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Commit c93bc959 authored by RD Babiera's avatar RD Babiera Committed by Greg Kroah-Hartman
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usb: typec: altmodes/displayport: do not index invalid pin_assignments 



commit af4db5a35a4ef7a68046883bfd12468007db38f1 upstream.

A poorly implemented DisplayPort Alt Mode port partner can indicate
that its pin assignment capabilities are greater than the maximum
value, DP_PIN_ASSIGN_F. In this case, calls to pin_assignment_show
will cause a BRK exception due to an out of bounds array access.

Prevent for loop in pin_assignment_show from accessing
invalid values in pin_assignments by adding DP_PIN_ASSIGN_MAX
value in typec_dp.h and using i < DP_PIN_ASSIGN_MAX as a loop
condition.

Fixes: 0e3bb7d6 ("usb: typec: Add driver for DisplayPort alternate mode")
Cc: stable <stable@kernel.org>
Signed-off-by: default avatarRD Babiera <rdbabiera@google.com>
Reviewed-by: default avatarBadhri Jagan Sridharan <badhri@google.com>
Reviewed-by: default avatarHeikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20250618224943.3263103-2-rdbabiera@google.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e7e91494

drivers/usb/typec/altmodes/displayport.c

+1 −1
Original line number Diff line number Diff line
@@ -492,7 +492,7 @@ static ssize_t pin_assignment_show(struct device *dev, 


	assignments = get_current_pin_assignments(dp);



	for (i = 0; assignments; assignments >>= 1, i++) {

	for (i = 0; assignments && i < DP_PIN_ASSIGN_MAX; assignments >>= 1, i++) {

		if (assignments & 1) {

			if (i == cur)

				len += sprintf(buf + len, "[%s] ",

include/linux/usb/typec_dp.h

+1 −0
Original line number Diff line number Diff line
@@ -56,6 +56,7 @@ enum { 
	DP_PIN_ASSIGN_D,

	DP_PIN_ASSIGN_E,

	DP_PIN_ASSIGN_F, /* Not supported after v1.0b */

	DP_PIN_ASSIGN_MAX,

};



/* DisplayPort alt mode specific commands */