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 <[email protected]>
Closes: https://lore.kernel.org/lkml/2023062945-fencing-pebble-0411@gregkh/
Reported-by: Mirsad Todorovac <[email protected]>
Closes: https://lore.kernel.org/lkml/[email protected]/
Cc: Greg Kroah-Hartman <[email protected]>
Cc: "Gustavo A. R. Silva" <[email protected]>
Tested-by: "Borislav Petkov (AMD)" <[email protected]>
Tested-by: Mirsad Todorovac <[email protected]>
Reviewed-by: "Gustavo A. R. Silva" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Kees Cook <[email protected]>

0 files changed, 0 insertions, 0 deletions