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gpiolib: cdev: annotate struct linereq with __counted_by

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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

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
This commit is contained in:
Kees Cook 2023-09-22 10:52:03 -07:00 • committed by Bartosz Golaszewski
parent 9f93f18305
commit a512635da9
1 changed files with 2 additions and 2 deletions
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4
drivers/gpio/gpiolib-cdev.c
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@ -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++) {