Prepare for the coming implementation by GCC and Clang of the __counted_by attribute. Flexible array members annotated with __counted_by can have their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family functions).
As found with Coccinelle[1], add __counted_by for struct linereq. Additionally, since the element count member must be set before accessing the annotated flexible array member, move its initialization earlier. [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci Cc: Linus Walleij <linus.wall...@linaro.org> Cc: Bartosz Golaszewski <b...@bgdev.pl> Cc: Andy Shevchenko <a...@kernel.org> Cc: linux-g...@vger.kernel.org Signed-off-by: Kees Cook <keesc...@chromium.org> --- drivers/gpio/gpiolib-cdev.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c index e39d344feb28..31fc71a612c2 100644 --- a/drivers/gpio/gpiolib-cdev.c +++ b/drivers/gpio/gpiolib-cdev.c @@ -572,7 +572,7 @@ struct linereq { DECLARE_KFIFO_PTR(events, struct gpio_v2_line_event); atomic_t seqno; struct mutex config_mutex; - struct line lines[]; + struct line lines[] __counted_by(num_lines); }; #define GPIO_V2_LINE_BIAS_FLAGS \ @@ -1656,6 +1656,7 @@ static int linereq_create(struct gpio_device *gdev, void __user *ip) lr = kzalloc(struct_size(lr, lines, ulr.num_lines), GFP_KERNEL); if (!lr) return -ENOMEM; + lr->num_lines = ulr.num_lines; lr->gdev = gpio_device_get(gdev); @@ -1684,7 +1685,6 @@ static int linereq_create(struct gpio_device *gdev, void __user *ip) lr->event_buffer_size = GPIO_V2_LINES_MAX * 16; atomic_set(&lr->seqno, 0); - lr->num_lines = ulr.num_lines; /* Request each GPIO */ for (i = 0; i < ulr.num_lines; i++) { -- 2.34.1
