power: supply: cros_usbpd-charger: bound the EC-reported port count

Overview

In the Linux kernel, the following vulnerability has been resolved:

power: supply: cros_usbpd-charger: bound the EC-reported port count

cros_usbpd_charger_probe() reads two port counts from the EC and uses one of them, num_charger_ports, as the loop bound when populating a fixed-size array:

struct port_data *ports[EC_USB_PD_MAX_PORTS];	/* 8 entries */
...
for (i = 0; i < charger->num_charger_ports; i++)
	charger->ports[charger->num_registered_psy++] = port;

Both num_usbpd_ports (from EC_CMD_USB_PD_PORTS) and num_charger_ports (from EC_CMD_CHARGE_PORT_COUNT) are u8 values reported by the EC. The only validation is a sanity check that compares the two EC-reported values against each other:

if (num_charger_ports < num_usbpd_ports ||
    num_charger_ports > num_usbpd_ports + 1)
	return -EPROTO;

It never checks either count against EC_USB_PD_MAX_PORTS, the size of the ports[] array. A malfunctioning, malicious or compromised EC that reports num_usbpd_ports == num_charger_ports == N for any N > 8 (for example both 255) passes this check, and the loop then writes N pointers into the 8-entry ports[] array embedded in the devm_kzalloc()'d charger_data, overflowing it by up to 255 - 8 = 247 entries (~1976 bytes): a slab out-of-bounds write.

Reject a port count larger than the ports[] array can hold.

Affected

• Linux >= f68b883e8fad23ed0ac4756d91594809d78678ed < 0b5096f6804161b61451b1cec0e38678630be849
• Linux >= f68b883e8fad23ed0ac4756d91594809d78678ed < c46c9f447415ca802afab51dea1eafc08ddff1c6
• Linux >= f68b883e8fad23ed0ac4756d91594809d78678ed < a1905375dfc0b9612bbee52fc066e3a70c0d671d
• Linux >= f68b883e8fad23ed0ac4756d91594809d78678ed < 2746d502b12b343384fb747bdef9cbcfbd7444a2
• Linux >= f68b883e8fad23ed0ac4756d91594809d78678ed < fd29d08ee487f3bf50f2575aaa74f78a74b09b21
• Linux >= f68b883e8fad23ed0ac4756d91594809d78678ed < 78be8b7403ff7638162438b664a07d19da76059e
• Linux >= f68b883e8fad23ed0ac4756d91594809d78678ed < 3d1e01443b221081258ff34ea0cdd0431e4ff62e
• Linux >= f68b883e8fad23ed0ac4756d91594809d78678ed < 48355ce49359740f52e94d3623f6fc557ce341f0
• Linux 4.19

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

Vendor advisories

• Red Hat VEX · Moderate · updated 2026-09-18 · vex