From: Jiri Olsa <jolsa@redhat.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andriin@fb.com>,
dwarves@vger.kernel.org, Networking <netdev@vger.kernel.org>,
bpf <bpf@vger.kernel.org>, Yonghong Song <yhs@fb.com>,
Hao Luo <haoluo@google.com>, Martin KaFai Lau <kafai@fb.com>,
Song Liu <songliubraving@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@chromium.org>,
Joe Lawrence <joe.lawrence@redhat.com>,
Mark Wielaard <mjw@redhat.com>
Subject: Re: [PATCH 1/3] elf_symtab: Add support for SHN_XINDEX index to elf_section_by_name
Date: Fri, 22 Jan 2021 00:34:05 +0100 [thread overview]
Message-ID: <20210121233405.GA14067@krava> (raw)
In-Reply-To: <CAEf4BzY5CSNjoe19V4GAbFM1N4o4jM38G6yahAhr5bAaDVcYxA@mail.gmail.com>
On Thu, Jan 21, 2021 at 03:10:25PM -0800, Andrii Nakryiko wrote:
> On Thu, Jan 21, 2021 at 12:24 PM Jiri Olsa <jolsa@kernel.org> wrote:
> >
> > In case the elf's header e_shstrndx contains SHN_XINDEX,
> > we need to call elf_getshdrstrndx to get the proper
> > string table index.
> >
> > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> > ---
> > dutil.c | 8 ++++++--
> > 1 file changed, 6 insertions(+), 2 deletions(-)
> >
> > diff --git a/dutil.c b/dutil.c
> > index 7b667647420f..9e0fdca3ae04 100644
> > --- a/dutil.c
> > +++ b/dutil.c
> > @@ -179,13 +179,17 @@ Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
> > {
> > Elf_Scn *sec = NULL;
> > size_t cnt = 1;
> > + size_t str_idx;
> > +
> > + if (elf_getshdrstrndx(elf, &str_idx))
> > + return NULL;
> >
> > while ((sec = elf_nextscn(elf, sec)) != NULL) {
> > char *str;
> >
> > gelf_getshdr(sec, shp);
> > - str = elf_strptr(elf, ep->e_shstrndx, shp->sh_name);
> > - if (!strcmp(name, str)) {
> > + str = elf_strptr(elf, str_idx, shp->sh_name);
> > + if (str && !strcmp(name, str)) {
>
> if (!str) would be an error? should we bail out here?
seems like if elf_nextscn returns NULL, it will be the case for all the
sections in here.. but bailing out on (!str) is more direct and safer
I'll send an update
thanks,
jirka
>
> > if (index)
> > *index = cnt;
> > break;
> > --
> > 2.27.0
> >
>
next prev parent reply other threads:[~2021-01-21 23:35 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-21 20:22 [PATCHv2 0/3] dwarves,libbpf: Add support to use optional extended section index table Jiri Olsa
2021-01-21 20:22 ` [PATCH 1/3] elf_symtab: Add support for SHN_XINDEX index to elf_section_by_name Jiri Olsa
2021-01-21 23:10 ` Andrii Nakryiko
2021-01-21 23:34 ` Jiri Olsa [this message]
2021-01-21 20:22 ` [PATCH 2/3] bpf_encoder: Translate SHN_XINDEX in symbol's st_shndx values Jiri Olsa
2021-01-21 23:32 ` Andrii Nakryiko
2021-01-22 9:32 ` Jiri Olsa
2021-01-22 20:46 ` Jiri Olsa
2021-01-22 22:55 ` Andrii Nakryiko
2021-01-23 18:51 ` Jiri Olsa
2021-01-23 20:07 ` Andrii Nakryiko
2021-01-23 20:21 ` Mark Wielaard
2021-01-23 20:08 ` Mark Wielaard
2021-01-23 20:15 ` Jiri Olsa
2021-01-23 21:23 ` Jiri Olsa
2021-01-24 6:08 ` Andrii Nakryiko
2021-01-21 20:22 ` [PATCH bpf-next 3/3] libbpf: Use string table index from index table if needed Jiri Olsa
2021-01-21 23:46 ` Andrii Nakryiko
-- strict thread matches above, loose matches on Subject: below --
2021-01-19 22:12 [PATCH 0/3] dwarves,libbpf: Add support to use optional extended section index table Jiri Olsa
2021-01-19 22:12 ` [PATCH 1/3] elf_symtab: Add support for SHN_XINDEX index to elf_section_by_name Jiri Olsa
2021-01-20 1:23 ` Andrii Nakryiko
2021-01-20 12:20 ` Jiri Olsa
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