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[2001:1ae9:1c2:4c00:726e:c10f:8833:ff22]) by smtp.gmail.com with ESMTPSA id pw18-20020a17090720b200b00a35c1d11621sm1985179ejb.131.2024.01.30.03.20.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 Jan 2024 03:20:08 -0800 (PST) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Tue, 30 Jan 2024 12:20:06 +0100 To: Anton Protopopov Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Martin KaFai Lau , Stanislav Fomichev , Yonghong Song , Eduard Zingerman , bpf@vger.kernel.org Subject: Re: [RFC PATCH bpf-next 1/5] bpf: fix potential error return Message-ID: References: <20240122164936.810117-1-aspsk@isovalent.com> <20240122164936.810117-2-aspsk@isovalent.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240122164936.810117-2-aspsk@isovalent.com> On Mon, Jan 22, 2024 at 04:49:32PM +0000, Anton Protopopov wrote: > The bpf_remove_insns() function returns WARN_ON_ONCE(error), where > error is a result of bpf_adj_branches(), and thus should be always 0 > However, if for any reason it is not 0, then it will be converted to > boolean by WARN_ON_ONCE and returned to user space as 1, not an actual > error value. Fix this by returning the original err after the WARN check. > > Signed-off-by: Anton Protopopov nice catch Acked-by: Jiri Olsa > --- > kernel/bpf/core.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c > index fbb1d95a9b44..9ba9e0ea9c45 100644 > --- a/kernel/bpf/core.c > +++ b/kernel/bpf/core.c > @@ -532,6 +532,8 @@ struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off, > > int bpf_remove_insns(struct bpf_prog *prog, u32 off, u32 cnt) > { > + int err; > + > /* Branch offsets can't overflow when program is shrinking, no need > * to call bpf_adj_branches(..., true) here > */ > @@ -539,7 +541,12 @@ int bpf_remove_insns(struct bpf_prog *prog, u32 off, u32 cnt) > sizeof(struct bpf_insn) * (prog->len - off - cnt)); > prog->len -= cnt; > > - return WARN_ON_ONCE(bpf_adj_branches(prog, off, off + cnt, off, false)); > + err = bpf_adj_branches(prog, off, off + cnt, off, false); > + WARN_ON_ONCE(err); > + if (err) > + return err; > + > + return 0; could be just 'return err' jirka > } > > static void bpf_prog_kallsyms_del_subprogs(struct bpf_prog *fp) > -- > 2.34.1 >