usb: ljca: bound bank_num in ljca_enumerate_gpio()

ljca_enumerate_gpio() reads desc->bank_num from the device and loops
valid_pin[i] = get_unaligned_le32(...) for i < bank_num. valid_pin[]
holds only LJCA_MAX_GPIO_NUM / 32 = 2 entries.

Two checks run before the loop. The reply length must match
struct_size(desc, bank_desc, bank_num). The product
pins_per_bank * bank_num must not exceed LJCA_MAX_GPIO_NUM. Neither one
bounds bank_num against the size of valid_pin[]. The reply is capped at
LJCA_MAX_PAYLOAD_SIZE (60) bytes, so the struct_size check limits
bank_num to 9. A device that reports bank_num 9 with pins_per_bank 7
still passes both checks. gpio_num is 63 and the reply is 56 bytes. The
loop then writes nine u32 into the two entry array and overruns
valid_pin[] on the stack.

A broken or malicious LJCA device can therefore overflow the stack.
Reject a bank_num that does not fit valid_pin[].

Fixes: acd6199f195d ("usb: Add support for Intel LJCA device")
Signed-off-by: Maoyi Xie <maoyixie.tju@gmail.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Link: https://patch.msgid.link/178176358875.3352358.6059116660356914900@maoyixie.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

0 files changed, 0 insertions, 0 deletions