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

I’ve reverted for now & reopened the Phabricator review.

Andrew

> On 15 Nov 2022, at 08:22, Mateusz Guzik <mjguzik@gmail.com> wrote:
> 
> 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>
>