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usb: typec: ucsi: validate connector number in ucsi_notify_common()

The connector number extracted from CCI via UCSI_CCI_CONNECTOR() is a
7-bit field (0-127) that is used to index into the connector array in
ucsi_connector_change(). However, the array is only allocated for the
number of connectors reported by the device (typically 2-4 entries).

A malicious or malfunctioning device could report an out-of-range
connector number in the CCI, causing an out-of-bounds array access in
ucsi_connector_change().

Add a bounds check in ucsi_notify_common(), the central point where CCI
is parsed after arriving from hardware, so that bogus connector numbers
are rejected before they propagate further.

Fixes: bdc62f2bae8f ("usb: typec: ucsi: Simplified registration and I/O API")
Cc: stable <stable@kernel.org>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Nathan Rebello <nathan.c.rebello@gmail.com>
Link: https://patch.msgid.link/20260313222453.123-1-nathan.c.rebello@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

authored by

Nathan Rebello and committed by
Greg Kroah-Hartman d2d8c17a 8a768552

+7 -2
+7 -2
drivers/usb/typec/ucsi/ucsi.c
··· 43 43 if (cci & UCSI_CCI_BUSY) 44 44 return; 45 45 46 - if (UCSI_CCI_CONNECTOR(cci)) 47 - ucsi_connector_change(ucsi, UCSI_CCI_CONNECTOR(cci)); 46 + if (UCSI_CCI_CONNECTOR(cci)) { 47 + if (UCSI_CCI_CONNECTOR(cci) <= ucsi->cap.num_connectors) 48 + ucsi_connector_change(ucsi, UCSI_CCI_CONNECTOR(cci)); 49 + else 50 + dev_err(ucsi->dev, "bogus connector number in CCI: %lu\n", 51 + UCSI_CCI_CONNECTOR(cci)); 52 + } 48 53 49 54 if (cci & UCSI_CCI_ACK_COMPLETE && 50 55 test_and_clear_bit(ACK_PENDING, &ucsi->flags))