From 01f23c5f1526f5b6ff744887aa511b9e69d4401b Mon Sep 17 00:00:00 2001
From: Kees Cook <keescook@chromium.org>
Date: Thu, 29 Jun 2023 12:09:00 -0700
Subject: [PATCH] usb: ch9: Replace bmSublinkSpeedAttr 1-element array with
flexible array
Since commit 2d47c6956ab3 ("ubsan: Tighten UBSAN_BOUNDS on GCC"),
UBSAN_BOUNDS no longer pretends 1-element arrays are unbounded. Walking
bmSublinkSpeedAttr will trigger a warning, so make it a proper flexible
array. Add a union to keep the struct size identical for userspace in
case anything was depending on the old size.
False positive warning was:
UBSAN: array-index-out-of-bounds in drivers/usb/host/xhci-hub.c:231:31 index 1 is out of range for type '__le32 [1]'
for this line of code:
ssp_cap->bmSublinkSpeedAttr[offset++] = cpu_to_le32(attr);
Reported-by: Borislav Petkov <bp@alien8.de>
Closes: https://lore.kernel.org/lkml/2023062945-fencing-pebble-0411@gregkh/
Reported-by: Mirsad Todorovac <mirsad.todorovac@alu.unizg.hr>
Closes: https://lore.kernel.org/lkml/9a8e34ad-8a8b-3830-4878-3c2c82e69dd9@alu.unizg.hr/
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Tested-by: "Borislav Petkov (AMD)" <bp@alien8.de>
Tested-by: Mirsad Todorovac <mirsad.todorovac@alu.unizg.hr>
Reviewed-by: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20230629190900.never.787-kees@kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
include/uapi/linux/usb/ch9.h | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/include/uapi/linux/usb/ch9.h b/include/uapi/linux/usb/ch9.h
index b17e3a21b15fb..3ff98c7ba7e3f 100644
--- a/include/uapi/linux/usb/ch9.h
+++ b/include/uapi/linux/usb/ch9.h
@@ -981,7 +981,11 @@ struct usb_ssp_cap_descriptor {
#define USB_SSP_MIN_RX_LANE_COUNT (0xf << 8)
#define USB_SSP_MIN_TX_LANE_COUNT (0xf << 12)
__le16 wReserved;
- __le32 bmSublinkSpeedAttr[1]; /* list of sublink speed attrib entries */
+ union {
+ __le32 legacy_padding;
+ /* list of sublink speed attrib entries */
+ __DECLARE_FLEX_ARRAY(__le32, bmSublinkSpeedAttr);
+ };
#define USB_SSP_SUBLINK_SPEED_SSID (0xf) /* sublink speed ID */
#define USB_SSP_SUBLINK_SPEED_LSE (0x3 << 4) /* Lanespeed exponent */
#define USB_SSP_SUBLINK_SPEED_LSE_BPS 0
--
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