On 3/4/24 3:19 PM, Kees Cook wrote:
FORTIFY_SOURCE has been ignoring 0-sized destinations while the kernel code base has been converted to flexible arrays. In order to enforce the 0-sized destinations (e.g. with __counted_by), the remaining 0-sized destinations need to be handled. Instead of converting an empty struct into using a flexible array, just directly use a pointer without any additional indirection. Remove struct gb_bootrom_get_firmware_response and struct gb_fw_download_fetch_firmware_response. Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Thanks for adding the comments! This looks good to me.
Reviewed-by: Alex Elder <elder@xxxxxxxxxx>
I want to call attention to a few other spots that should
get a little more attention--related directly to what you're
doing here.
I noticed that the GB_CONTROL_TYPE_GET_MANIFEST response
structure also contains only a flexible array. It might
be good to add a similar comment in gb_interface_enable(),
above this line:
manifest = kmalloc(size, GFP_KERNEL);
The definition of the gb_control_get_manifest_response structure
could probably be replaced with a comment.
The response buffer for an I2C transfer consists only of incoming
data. There is already a comment in gb_i2c_operation_create()
that says this:
/* Response consists only of incoming data */
The definition of the gb_i2c_transfer_response structure should
then go away, in favor of a comment saying this.
The response buffer for a SPI transfer consists only of incoming
data. It is used three times in "driver/staging/greybus/spilib.c":
- calc_rx_xfer_size() subtracts the size of the response structure,
and that should be replaced by a comment (and the structure
definition should go away)
- gb_spi_decode_response() takes the response structure as an
argument. That could be replaced with a void pointer instead,
with a comment.
- gb_spi_transfer_one_message() is what passes the response buffer
to gb_spi_decode_response(), and could be adjusted to reflect
that the response consists only of data--rather than a struct
containing only a flexible array.
Kees: I'm *not* asking you to deal with these, I'm just mentioning
them to you. My comments above (without someone else confirming)
are not sufficient to dictate how to address these.
-Alex
--- Cc: Alex Elder <elder@xxxxxxxxxx> Cc: Viresh Kumar <vireshk@xxxxxxxxxx> Cc: Johan Hovold <johan@xxxxxxxxxx> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Cc: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx> Cc: greybus-dev@xxxxxxxxxxxxxxxx Cc: linux-staging@xxxxxxxxxxxxxxx v2: add comments about removed structs v1: https://patchwork.kernel.org/project/linux-hardening/patch/20240216232824.work.862-kees@xxxxxxxxxx/ --- drivers/staging/greybus/bootrom.c | 8 ++++---- drivers/staging/greybus/fw-download.c | 8 ++++---- include/linux/greybus/greybus_protocols.h | 8 ++------ 3 files changed, 10 insertions(+), 14 deletions(-) diff --git a/drivers/staging/greybus/bootrom.c b/drivers/staging/greybus/bootrom.c index 79581457c4af..c0d338db6b52 100644 --- a/drivers/staging/greybus/bootrom.c +++ b/drivers/staging/greybus/bootrom.c @@ -243,10 +243,10 @@ static int gb_bootrom_get_firmware(struct gb_operation *op) struct gb_bootrom *bootrom = gb_connection_get_data(op->connection); const struct firmware *fw; struct gb_bootrom_get_firmware_request *firmware_request; - struct gb_bootrom_get_firmware_response *firmware_response; struct device *dev = &op->connection->bundle->dev; unsigned int offset, size; enum next_request_type next_request; + u8 *firmware_response; int ret = 0;/* Disable timeouts */@@ -280,15 +280,15 @@ static int gb_bootrom_get_firmware(struct gb_operation *op) goto unlock; }- if (!gb_operation_response_alloc(op, sizeof(*firmware_response) + size,- GFP_KERNEL)) { + /* gb_bootrom_get_firmware_response contains only a byte array */ + if (!gb_operation_response_alloc(op, size, GFP_KERNEL)) { dev_err(dev, "%s: error allocating response\n", __func__); ret = -ENOMEM; goto unlock; }firmware_response = op->response->payload;- memcpy(firmware_response->data, fw->data + offset, size); + memcpy(firmware_response, fw->data + offset, size);dev_dbg(dev, "responding with firmware (offs = %u, size = %u)\n",offset, size); diff --git a/drivers/staging/greybus/fw-download.c b/drivers/staging/greybus/fw-download.c index 543692c567f9..a06065fb0c5e 100644 --- a/drivers/staging/greybus/fw-download.c +++ b/drivers/staging/greybus/fw-download.c @@ -271,11 +271,11 @@ static int fw_download_fetch_firmware(struct gb_operation *op) struct gb_connection *connection = op->connection; struct fw_download *fw_download = gb_connection_get_data(connection); struct gb_fw_download_fetch_firmware_request *request; - struct gb_fw_download_fetch_firmware_response *response; struct fw_request *fw_req; const struct firmware *fw; unsigned int offset, size; u8 firmware_id; + u8 *response; int ret = 0;if (op->request->payload_size != sizeof(*request)) {@@ -325,8 +325,8 @@ static int fw_download_fetch_firmware(struct gb_operation *op) goto put_fw; }- if (!gb_operation_response_alloc(op, sizeof(*response) + size,- GFP_KERNEL)) { + /* gb_fw_download_fetch_firmware_response contains only a byte array */ + if (!gb_operation_response_alloc(op, size, GFP_KERNEL)) { dev_err(fw_download->parent, "error allocating fetch firmware response\n"); ret = -ENOMEM; @@ -334,7 +334,7 @@ static int fw_download_fetch_firmware(struct gb_operation *op) }response = op->response->payload;- memcpy(response->data, fw->data + offset, size); + memcpy(response, fw->data + offset, size);dev_dbg(fw_download->parent,"responding with firmware (offs = %u, size = %u)\n", offset, diff --git a/include/linux/greybus/greybus_protocols.h b/include/linux/greybus/greybus_protocols.h index aeb8f9243545..820134b0105c 100644 --- a/include/linux/greybus/greybus_protocols.h +++ b/include/linux/greybus/greybus_protocols.h @@ -232,9 +232,7 @@ struct gb_fw_download_fetch_firmware_request { __le32 size; } __packed;-struct gb_fw_download_fetch_firmware_response {- __u8 data[0]; -} __packed; +/* gb_fw_download_fetch_firmware_response contains no other data *//* firmware download release firmware request */struct gb_fw_download_release_firmware_request { @@ -414,9 +412,7 @@ struct gb_bootrom_get_firmware_request { __le32 size; } __packed;-struct gb_bootrom_get_firmware_response {- __u8 data[0]; -} __packed; +/* gb_bootrom_get_firmware_response contains no other data *//* Bootrom protocol Ready to boot request */struct gb_bootrom_ready_to_boot_request {
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