5.4-stable review patch. If anyone has any objections, please let me know.
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From: RD Babiera rdbabiera@google.com
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: 0e3bb7d6894d ("usb: typec: Add driver for DisplayPort alternate mode") Cc: stable stable@kernel.org Signed-off-by: RD Babiera rdbabiera@google.com Reviewed-by: Badhri Jagan Sridharan badhri@google.com Reviewed-by: Heikki Krogerus heikki.krogerus@linux.intel.com Link: https://lore.kernel.org/r/20250618224943.3263103-2-rdbabiera@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/typec/altmodes/displayport.c | 2 +- include/linux/usb/typec_dp.h | 1 + 2 files changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/usb/typec/altmodes/displayport.c +++ b/drivers/usb/typec/altmodes/displayport.c @@ -492,7 +492,7 @@ static ssize_t pin_assignment_show(struc
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] ", --- a/include/linux/usb/typec_dp.h +++ b/include/linux/usb/typec_dp.h @@ -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 */