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Fri, 01 Aug 2025 09:09:36 -0700 (PDT) Message-ID: <5e7b3c728c88b238224d3dffde4abbd7567b8d1c.camel@gmail.com> Subject: Re: [PATCH bpf 3/4] bpf: Improve ctx access verifier error message From: Eduard Zingerman To: Paul Chaignon , bpf@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , netfilter-devel@vger.kernel.org, Pablo Neira Ayuso , Jozsef Kadlecsik , Petar Penkov , Florian Westphal Date: Fri, 01 Aug 2025 09:09:33 -0700 In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.56.2 (3.56.2-1.fc42) Precedence: bulk X-Mailing-List: netfilter-devel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Fri, 2025-08-01 at 11:49 +0200, Paul Chaignon wrote: > We've already had two "error during ctx access conversion" warnings > triggered by syzkaller. Let's improve the error message by dumping the > cnt variable so that we can more easily differentiate between the > different error cases. >=20 > Signed-off-by: Paul Chaignon > --- Acked-by: Eduard Zingerman > kernel/bpf/verifier.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) >=20 > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c > index 399f03e62508..0806295945e4 100644 > --- a/kernel/bpf/verifier.c > +++ b/kernel/bpf/verifier.c > @@ -21445,7 +21445,7 @@ static int convert_ctx_accesses(struct bpf_verifi= er_env *env) > &target_size); > if (cnt =3D=3D 0 || cnt >=3D INSN_BUF_SIZE || > (ctx_field_size && !target_size)) { > - verifier_bug(env, "error during ctx access conversion"); > + verifier_bug(env, "error during ctx access conversion (%d)", cnt); Nit: maybe print the rest of the fields as well? > return -EFAULT; > } > =20