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Date:      Tue, 15 Nov 2022 12:42:03 +0000
From:      Andrew Turner <andrew@fubar.geek.nz>
To:        Mateusz Guzik <mjguzik@gmail.com>
Cc:        Brooks Davis <brooks@freebsd.org>, "<src-committers@freebsd.org>" <src-committers@freebsd.org>, "<dev-commits-src-all@freebsd.org>" <dev-commits-src-all@freebsd.org>, dev-commits-src-main@freebsd.org
Subject:   Re: git: 40e0fa10f58d - main - Check alignment of fp in unwind_frame
Message-ID:  <30B11BD5-A1B5-4513-8C0D-8BA89C12C55A@fubar.geek.nz>
In-Reply-To: <CAGudoHGZhUjOs4a-A8mW7oo49HcfxbvVDx5CfULQTF-GN6OkuA@mail.gmail.com>
References:  <202211150026.2AF0Q9vH048757@gitrepo.freebsd.org> <CAGudoHGZhUjOs4a-A8mW7oo49HcfxbvVDx5CfULQTF-GN6OkuA@mail.gmail.com>

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I=E2=80=99ve reverted for now & reopened the Phabricator review.

Andrew

> On 15 Nov 2022, at 08:22, Mateusz Guzik <mjguzik@gmail.com> wrote:
>=20
> this fails to build:
>=20
> /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.
>=20
> On 11/15/22, Brooks Davis <brooks@freebsd.org> wrote:
>> The branch main has been updated by brooks:
>>=20
>> URL:
>> =
https://cgit.FreeBSD.org/src/commit/?id=3D40e0fa10f58d90744c2857b57adf0ddb=
ce1a1e1c
>>=20
>> 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
>>=20
>>    Check alignment of fp in unwind_frame
>>=20
>>    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.
>>=20
>>    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(-)
>>=20
>> 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)
>>=20
>> 	fp =3D frame->fp;
>>=20
>> -	if (!kstack_contains(td, fp, sizeof(uintptr_t) * 2))
>> +	if (!is_aligned(fp, sizeof(fp)) ||
>> +	    !kstack_contains(td, fp, sizeof(fp) * 2))
>> 		return (false);
>>=20
>> 	/* 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)
>>=20
>> 	fp =3D frame->fp;
>>=20
>> -	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);
>>=20
>> 	frame->sp =3D fp;
>>=20
>=20
>=20
> --=20
> Mateusz Guzik <mjguzik gmail.com>
>=20




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