From 48355ce49359740f52e94d3623f6fc557ce341f0 Mon Sep 17 00:00:00 2001 From: Bryam Vargas Date: Tue, 16 Jun 2026 23:59:45 -0500 Subject: [PATCH] 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. Fixes: f68b883e8fad ("power: supply: add cros-ec USBPD charger driver.") Cc: stable@vger.kernel.org Signed-off-by: Bryam Vargas Reviewed-by: Tzung-Bi Shih Link: https://patch.msgid.link/20260616-b4-disp-5e197080-v2-1-8aa5bffce945@proton.me Signed-off-by: Sebastian Reichel --- drivers/power/supply/cros_usbpd-charger.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/power/supply/cros_usbpd-charger.c b/drivers/power/supply/cros_usbpd-charger.c index 308e1d4e6dd8..e410048aa0ab 100644 --- a/drivers/power/supply/cros_usbpd-charger.c +++ b/drivers/power/supply/cros_usbpd-charger.c @@ -589,10 +589,13 @@ static int cros_usbpd_charger_probe(struct platform_device *pd) /* * Sanity checks on the number of ports: - * there should be at most 1 dedicated port + * there should be at most 1 dedicated port, and the count must + * not exceed the maximum number of supported ports + * (EC_USB_PD_MAX_PORTS). */ if (charger->num_charger_ports < charger->num_usbpd_ports || - charger->num_charger_ports > (charger->num_usbpd_ports + 1)) { + charger->num_charger_ports > (charger->num_usbpd_ports + 1) || + charger->num_charger_ports > EC_USB_PD_MAX_PORTS) { dev_err(dev, "Unexpected number of charge port count\n"); ret = -EPROTO; goto fail_nowarn;