netdev - [PATCH 1/3] elf_symtab: Add support for SHN_XINDEX index to elf_section_by

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Message-Id: <20210119221220.1745061-2-jolsa@kernel.org>
Date:   Tue, 19 Jan 2021 23:12:18 +0100
From:   Jiri Olsa <jolsa@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andriin@...com>
Cc:     dwarves@...r.kernel.org, netdev@...r.kernel.org,
        bpf@...r.kernel.org, Yonghong Song <yhs@...com>,
        Hao Luo <haoluo@...gle.com>, Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        Joe Lawrence <joe.lawrence@...hat.com>,
        Mark Wielaard <mjw@...hat.com>
Subject: [PATCH 1/3] elf_symtab: Add support for SHN_XINDEX index to elf_section_by_name

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@...nel.org>
---
 dutil.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/dutil.c b/dutil.c
index 7b667647420f..321f4be6669e 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 shstrndx = ep->e_shstrndx;
+
+	if (shstrndx == SHN_XINDEX && elf_getshdrstrndx(elf, &shstrndx))
+		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, shstrndx, shp->sh_name);
+		if (str && !strcmp(name, str)) {
 			if (index)
 				*index = cnt;
 			break;
-- 
2.27.0