| Message ID | 20240304211940.it.083-kees@kernel.org (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | 7ba59ac7da2aae2fbcfe90352ee40d30cecca10d |
| Headers | show |
| Series | [v2] greybus: Avoid fake flexible array for response data | expand |
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@chromium.org> Thanks for adding the comments! This looks good to me. Reviewed-by: Alex Elder <elder@linaro.org> 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@kernel.org> > Cc: Viresh Kumar <vireshk@kernel.org> > Cc: Johan Hovold <johan@kernel.org> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Cc: Gustavo A. R. Silva <gustavo@embeddedor.com> > Cc: greybus-dev@lists.linaro.org > Cc: linux-staging@lists.linux.dev > v2: add comments about removed structs > v1: https://patchwork.kernel.org/project/linux-hardening/patch/20240216232824.work.862-kees@kernel.org/ > --- > 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 {
On Mon, Mar 04, 2024 at 04:45:11PM -0600, Alex Elder wrote: > 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@chromium.org> > > Thanks for adding the comments! This looks good to me. > > Reviewed-by: Alex Elder <elder@linaro.org> > > > > 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. Okay, thanks! Yeah, I took a look at struct gb_i2c_transfer_response and I think it might trip the memcpy checking too since it's zero sized, but it's on the source side, which isn't as strictly checked. I'll add a TODO item to track these, though. -Kees
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 {
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@chromium.org> --- Cc: Alex Elder <elder@kernel.org> Cc: Viresh Kumar <vireshk@kernel.org> Cc: Johan Hovold <johan@kernel.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Gustavo A. R. Silva <gustavo@embeddedor.com> Cc: greybus-dev@lists.linaro.org Cc: linux-staging@lists.linux.dev v2: add comments about removed structs v1: https://patchwork.kernel.org/project/linux-hardening/patch/20240216232824.work.862-kees@kernel.org/ --- 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(-)