From: KP Singh <kpsingh@chromium.org>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>,
open list <linux-kernel@vger.kernel.org>,
bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Paul Turner <pjt@google.com>,
Florent Revest <revest@chromium.org>,
Brendan Jackman <jackmanb@chromium.org>
Subject: Re: [PATCH bpf-next 4/7] bpf: Attachment verification for BPF_MODIFY_RETURN
Date: Wed, 4 Mar 2020 02:06:15 +0100 [thread overview]
Message-ID: <20200304010615.GA14634@chromium.org> (raw)
In-Reply-To: <20200304000326.nk7jmkgxazl3umbh@ast-mbp>
On 03-Mär 16:03, Alexei Starovoitov wrote:
> On Wed, Mar 04, 2020 at 12:21:51AM +0100, KP Singh wrote:
> >
> > > > + t = btf_type_skip_modifiers(btf, t->type, NULL);
> > > > + if (!btf_type_is_int(t)) {
> > >
> > > Should the size of int be verified here? E.g., if some function
> > > returns u8, is that ok for BPF program to return, say, (1<<30) ?
> >
> > Would this work?
> >
> > if (size != t->size) {
> > bpf_log(log,
> > "size accessed = %d should be %d\n",
> > size, t->size);
> > return false;
> > }
>
> It will cause spurious failures later when llvm optimizes
> if (ret & 0xff) into u8 load.
> I think btf_type_is_int() is enough as-is.
Okay skipping the size check.
- KP
next prev parent reply other threads:[~2020-03-04 1:06 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-03 14:09 [PATCH bpf-next 0/7] Introduce BPF_MODIFY_RET tracing progs KP Singh
2020-03-03 14:09 ` [PATCH bpf-next 1/7] bpf: Refactor trampoline update code KP Singh
2020-03-03 22:12 ` Andrii Nakryiko
2020-03-03 22:24 ` KP Singh
2020-03-03 23:03 ` Andrii Nakryiko
2020-03-03 23:08 ` KP Singh
2020-03-03 14:09 ` [PATCH bpf-next 2/7] bpf: JIT helpers for fmod_ret progs KP Singh
2020-03-03 22:26 ` Andrii Nakryiko
2020-03-03 22:28 ` KP Singh
2020-03-03 23:56 ` Alexei Starovoitov
2020-03-04 1:26 ` KP Singh
2020-03-03 14:09 ` [PATCH bpf-next 3/7] bpf: Introduce BPF_MODIFY_RETURN KP Singh
2020-03-03 22:37 ` Andrii Nakryiko
2020-03-03 22:51 ` KP Singh
2020-03-03 14:09 ` [PATCH bpf-next 4/7] bpf: Attachment verification for BPF_MODIFY_RETURN KP Singh
2020-03-03 22:44 ` Andrii Nakryiko
2020-03-03 23:21 ` KP Singh
2020-03-04 0:03 ` Alexei Starovoitov
2020-03-04 1:06 ` KP Singh [this message]
2020-03-03 14:09 ` [PATCH bpf-next 5/7] tools/libbpf: Add support " KP Singh
2020-03-03 22:45 ` Andrii Nakryiko
2020-03-03 14:09 ` [PATCH bpf-next 6/7] bpf: Add test ops for BPF_PROG_TYPE_TRACING KP Singh
2020-03-03 22:51 ` Andrii Nakryiko
2020-03-03 22:57 ` KP Singh
2020-03-03 14:09 ` [PATCH bpf-next 7/7] bpf: Add selftests for BPF_MODIFY_RETURN KP Singh
2020-03-03 22:58 ` Andrii Nakryiko
2020-03-03 22:12 ` [PATCH bpf-next 0/7] Introduce BPF_MODIFY_RET tracing progs Andrii Nakryiko
2020-03-03 22:25 ` KP Singh
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