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AJvYcCUDKh93e9rE9KX3PeRkSELJjFXvFJwVdNkkPftObct26LQDr7iVlP7sGSg+bisxuqG+hWQ=@vger.kernel.org, AJvYcCVbb1f7jWZB6GEbXhl9OZaeFHJ3RjNp9txDIEJPTCVef8LJzxEB3vpW3nd4QSORRLTUGj43is1ej9hqlviD@vger.kernel.org X-Gm-Message-State: AOJu0YwHwCR7qxVwDn4xbXNUwuWqVyM7wxdCMJ9oyuFM8emNtXGp0X2R 7Q+MZt1elcFkR4wyjL8ietOer7/4jQY2v0pNwidOZX5g43PfTsuO X-Google-Smtp-Source: AGHT+IGHl7cemBtoX5qsT9N4v16xPV1yX2TOLZXitRI1QU88g9SCvxMpqVFWtfp3UkXmgk0SXrsj6Q== X-Received: by 2002:a05:6a20:2d24:b0:1c4:818c:2986 with SMTP id adf61e73a8af0-1cce100e21emr4887015637.13.1724983447328; Thu, 29 Aug 2024 19:04:07 -0700 (PDT) Received: from smtpclient.apple ([2001:e60:a014:2acf:bd3a:95a:cb6b:9c04]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-20515550badsm17508025ad.241.2024.08.29.19.04.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 29 Aug 2024 19:04:06 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable From: Jeongjun Park Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 (1.0) Subject: Re: [PATCH bpf] bpf: add check for invalid name in btf_name_valid_section() Date: Fri, 30 Aug 2024 11:03:54 +0900 Message-Id: <07EBE3E5-61A7-4F64-92BA-24A1DCA9583B@gmail.com> References: <3a48e38f29cc8c73e36a6d3339b9303571d522a8.camel@gmail.com> Cc: alexei.starovoitov@gmail.com, andrii@kernel.org, ast@kernel.org, bpf@vger.kernel.org, daniel@iogearbox.net, haoluo@google.com, john.fastabend@gmail.com, jolsa@kernel.org, kpsingh@kernel.org, linux-kernel@vger.kernel.org, martin.lau@linux.dev, sdf@fomichev.me, song@kernel.org, yonghong.song@linux.dev In-Reply-To: <3a48e38f29cc8c73e36a6d3339b9303571d522a8.camel@gmail.com> To: Eduard Zingerman X-Mailer: iPhone Mail (21F90) > Eduard Zingerman wrote: >=20 > =EF=BB=BFOn Wed, 2024-08-28 at 22:45 -0700, Eduard Zingerman wrote: >=20 > [...] >=20 >> I will prepare a test case. >> Probably tomorrow. >=20 > Please find test in the attachment. This test triggers KASAN error > report as in another attachment. (I enabled CONFIG_KASAN using > menuconfig on top of regular selftest config). >=20 Thank you for writing the selftest for me. > On Fri, Aug 23, 2024 at 3:43=E2=80=AFAM Jeongjun Park wrote: >=20 > [...] >=20 >> diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c >> index 520f49f422fe..5c24ea1a65a4 100644 >> --- a/kernel/bpf/btf.c >> +++ b/kernel/bpf/btf.c >> @@ -823,6 +823,9 @@ static bool btf_name_valid_section(const struct btf *= btf, u32 offset) >> const char *src =3D btf_str_by_offset(btf, offset); >> const char *src_limit; >>=20 >> + if (!*src) >> + return false; >> + >=20 > I think that correct fix would be as follows: >=20 > --- >=20 > diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c > index edad152cee8e..d583d76fcace 100644 > --- a/kernel/bpf/btf.c > +++ b/kernel/bpf/btf.c > @@ -820,7 +820,6 @@ static bool btf_name_valid_section(const struct btf *b= tf, u32 offset) >=20 > /* set a limit on identifier length */ > src_limit =3D src + KSYM_NAME_LEN; > - src++; > while (*src && src < src_limit) { > if (!isprint(*src)) > return false; However, this patch is logically flawed.=20 It will return true for invalid names with=20 length 1 and src[0] being NULL. So I think=20 it's better to stick with the original patch. >=20 > >