On Tue, Oct 10, 2023 at 5:47 AM Gustavo A. R. Silva
<gustavo...@kernel.org> wrote:
>
> 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 via CONFIG_UBSAN_BOUNDS (for
> array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
>
> While there, use struct_size() helper, instead of the open-coded
> version, to calculate the size for the allocation of the whole
> flexible structure, including of course, the flexible-array member.
>
> This code was found with the help of Coccinelle, and audited and
> fixed manually.
>
> Signed-off-by: Gustavo A. R. Silva <gustavo...@kernel.org>
Looks good to me.
Reviewed-by: Justin Stitt <justinst...@google.com>
> ---
> arch/arm/kernel/atags_proc.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm/kernel/atags_proc.c b/arch/arm/kernel/atags_proc.c
> index 3ec2afe78423..cd09f8ab93e3 100644
> --- a/arch/arm/kernel/atags_proc.c
> +++ b/arch/arm/kernel/atags_proc.c
> @@ -7,7 +7,7 @@
>
> struct buffer {
> size_t size;
> - char data[];
> + char data[] __counted_by(size);
> };
>
> static ssize_t atags_read(struct file *file, char __user *buf,
> @@ -54,7 +54,7 @@ static int __init init_atags_procfs(void)
>
> WARN_ON(tag->hdr.tag != ATAG_NONE);
>
> - b = kmalloc(sizeof(*b) + size, GFP_KERNEL);
> + b = kmalloc(struct_size(b, data, size), GFP_KERNEL);
> if (!b)
> goto nomem;
>
> --
> 2.34.1
>
>
Thanks
Justin
