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Date: Fri, 9 Sep 2022 14:43:18 -0700
From: sdf@...gle.com
To: Peilin Ye <yepeilin.cs@...il.com>
Cc: Benjamin Tissoires <benjamin.tissoires@...hat.com>,
Andrii Nakryiko <andrii@...nel.org>,
Alexei Starovoitov <ast@...nel.org>, bpf <bpf@...r.kernel.org>,
Daniel Borkmann <daniel@...earbox.net>, davem@...emloft.net,
haoluo@...gle.com, hawk@...nel.org,
John Fastabend <john.fastabend@...il.com>, jolsa@...nel.org,
KP Singh <kpsingh@...nel.org>, kuba@...nel.org,
lkml <linux-kernel@...r.kernel.org>, llvm@...ts.linux.dev,
martin.lau@...ux.dev, nathan@...nel.org,
Nick Desaulniers <ndesaulniers@...gle.com>,
Networking <netdev@...r.kernel.org>, Song Liu <song@...nel.org>,
syzkaller-bugs@...glegroups.com, Tom Rix <trix@...hat.com>,
Yonghong Song <yhs@...com>, Peilin Ye <peilin.ye@...edance.com>
Subject: Re: [syzbot] WARNING in bpf_verifier_vlog
On 09/09, Peilin Ye wrote:
> Hi all,
> On Fri, Sep 09, 2022 at 12:54:06PM -0700, sdf@...gle.com wrote:
> > On 09/09, Benjamin Tissoires wrote:
> > Yeah, good point. I've run the repro. I think the issue is that
> > syzkaller is able to pass btf with a super long random name which
> > then hits BPF_VERIFIER_TMP_LOG_SIZE while printing the verifier
> > log line. Seems like a non-issue to me, but maybe we need to
> > add some extra validation..
> In btf_func_proto_check_meta():
> if (t->name_off) {
> btf_verifier_log_type(env, t, "Invalid name");
> return -EINVAL;
> }
> In the verifier log, maybe we should just say that
> BTF_KIND_FUNC_PROTO "must
> not have a name" [1], instead of printing out the user-provided
> (potentially very long) name and say it's "Invalid" ?
> Similarly, for name-too-long errors, should we truncate the name to
> KSYM_NAME_LEN bytes (see __btf_name_valid()) in the log ?
Both suggestions sound good to me. Care to cook and send a patch with a
fix?
> [1] commit 2667a2626f4d ("bpf: btf: Add BTF_KIND_FUNC and
> BTF_KIND_FUNC_PROTO")
> Thanks,
> Peilin Ye
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