Re: git: 40e0fa10f58d - main - Check alignment of fp in unwind_frame

this fails to build:

/usr/src/sys/riscv/riscv/unwind.c:50:7: error: implicit declaration of
function 'is_aligned' is invalid in C99
[-Werror,-Wimplicit-function-declaration]
        if (!is_aligned(fp, sizeof(fp)) ||
             ^
1 error generated.

On 11/15/22, Brooks Davis <brooks@freebsd.org> wrote:
> The branch main has been updated by brooks:
>
> URL:
> https://cgit.FreeBSD.org/src/commit/?id=40e0fa10f58d90744c2857b57adf0ddbce1a1e1c
>
> commit 40e0fa10f58d90744c2857b57adf0ddbce1a1e1c
> Author:     Dapeng Gao <dapeng@dpgao.cn>
> AuthorDate: 2022-11-15 00:21:38 +0000
> Commit:     Brooks Davis <brooks@FreeBSD.org>
> CommitDate: 2022-11-15 00:25:46 +0000
>
>     Check alignment of fp in unwind_frame
>
>     A misaligned frame pointer is certainly not a valid frame pointer and
>     with strict alignment enabled (as on CHERI) can cause panics when it is
>     loaded from later in the code.
>
>     Reviewed By:    jhb
>     Differential Revision: https://reviews.freebsd.org/D34646
> ---
>  sys/arm64/arm64/unwind.c | 3 ++-
>  sys/riscv/riscv/unwind.c | 3 ++-
>  2 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/sys/arm64/arm64/unwind.c b/sys/arm64/arm64/unwind.c
> index 470b64c00540..81431e109494 100644
> --- a/sys/arm64/arm64/unwind.c
> +++ b/sys/arm64/arm64/unwind.c
> @@ -41,7 +41,8 @@ unwind_frame(struct thread *td, struct unwind_state
> *frame)
>
>  	fp = frame->fp;
>
> -	if (!kstack_contains(td, fp, sizeof(uintptr_t) * 2))
> +	if (!is_aligned(fp, sizeof(fp)) ||
> +	    !kstack_contains(td, fp, sizeof(fp) * 2))
>  		return (false);
>
>  	/* FP to previous frame (X29) */
> diff --git a/sys/riscv/riscv/unwind.c b/sys/riscv/riscv/unwind.c
> index 9efb1fef9451..a66ffebcdc35 100644
> --- a/sys/riscv/riscv/unwind.c
> +++ b/sys/riscv/riscv/unwind.c
> @@ -47,7 +47,8 @@ unwind_frame(struct thread *td, struct unwind_state
> *frame)
>
>  	fp = frame->fp;
>
> -	if (!kstack_contains(td, fp - sizeof(fp) * 2, sizeof(fp) * 2))
> +	if (!is_aligned(fp, sizeof(fp)) ||
> +	    !kstack_contains(td, fp - sizeof(fp) * 2, sizeof(fp) * 2))
>  		return (false);
>
>  	frame->sp = fp;
>


-- 
Mateusz Guzik <mjguzik gmail.com>