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([2620:10d:c090:600::1:56e6]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-76c0e86f3c6sm18226200b3a.5.2025.08.11.09.46.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 11 Aug 2025 09:46:35 -0700 (PDT) Message-ID: <6b72f32a9d1b137fb3f3ae0c439b1688fef8dd8d.camel@gmail.com> Subject: Re: [PATCH] bpf: replace kvfree with kfree for kzalloc memory From: Eduard Zingerman To: Qianfeng Rong , Alexei Starovoitov , Daniel Borkmann , John Fastabend , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , bpf@vger.kernel.org, linux-kernel@vger.kernel.org Date: Mon, 11 Aug 2025 09:46:33 -0700 In-Reply-To: <20250811123949.552885-1-rongqianfeng@vivo.com> References: <20250811123949.552885-1-rongqianfeng@vivo.com> 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: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Mon, 2025-08-11 at 20:39 +0800, Qianfeng Rong wrote: > The 'backedge' pointer is allocated with kzalloc(), which returns > physically contiguous memory. Using kvfree() to deallocate such > memory is functionally safe but semantically incorrect. >=20 > Replace kvfree() with kfree() to avoid unnecessary is_vmalloc_addr() > check in kvfree(). >=20 > Signed-off-by: Qianfeng Rong > --- 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 c4f69a9e9af6..4e5de1ff7e30 100644 > --- a/kernel/bpf/verifier.c > +++ b/kernel/bpf/verifier.c > @@ -19553,7 +19553,7 @@ static int is_state_visited(struct bpf_verifier_e= nv *env, int insn_idx) > err =3D err ?: add_scc_backedge(env, &sl->state, backedge); > if (err) { > free_verifier_state(&backedge->state, false); > - kvfree(backedge); > + kfree(backedge); The backedge encapsulates verifier state, verifier states are allocated using kzalloc() and freed using kfreed() in other places in verifier.c =3D> I think this patch is valid. > return err; > } > }