In the quest to remove all stack VLA usage from the kernel[1], this removes the VLA in favor of a maximum size and adds a sanity check. Existing callers of the firmware interface never need more than 24 bytes (struct gpio_set_config). This chooses 32 just to stay ahead of future growth.
[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qpxydaacu1rq...@mail.gmail.com Signed-off-by: Kees Cook <keesc...@chromium.org> --- drivers/firmware/raspberrypi.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c index 0602626bf72d..b80f15214b73 100644 --- a/drivers/firmware/raspberrypi.c +++ b/drivers/firmware/raspberrypi.c @@ -21,6 +21,8 @@ #define MBOX_DATA28(msg) ((msg) & ~0xf) #define MBOX_CHAN_PROPERTY 8 +#define MAX_RPI_FW_PROP_BUF_SIZE 32 + static struct platform_device *rpi_hwmon; struct rpi_firmware { @@ -145,11 +147,15 @@ int rpi_firmware_property(struct rpi_firmware *fw, /* Single tags are very small (generally 8 bytes), so the * stack should be safe. */ - u8 data[buf_size + sizeof(struct rpi_firmware_property_tag_header)]; + u8 data[sizeof(struct rpi_firmware_property_tag_header) + + MAX_RPI_FW_PROP_BUF_SIZE]; struct rpi_firmware_property_tag_header *header = (struct rpi_firmware_property_tag_header *)data; int ret; + if (WARN_ON(buf_size > sizeof(data) - sizeof(*header))) + return -EINVAL; + header->tag = tag; header->buf_size = buf_size; header->req_resp_size = 0; -- 2.17.1 -- Kees Cook Pixel Security
