From: Andrii Nakryiko <andrii@xxxxxxxxxx>
[ Upstream commit 0d6988e16a12ebd41d3e268992211b0ceba44ed7 ]
e_shnum does include section #0 and as such is exactly the number of ELF
sections that we need to allocate memory for to use section indices as
array indices. Fix the off-by-one error.
This is purely accounting fix, previously we were overallocating one
too many array items. But no correctness errors otherwise.
Fixes: 25bbbd7a444b ("libbpf: Remove assumptions about uniqueness of .rodata/.data/.bss maps")
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Acked-by: Yonghong Song <yhs@xxxxxx>
Link: https://lore.kernel.org/bpf/20211103173213.1376990-5-andrii@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
tools/lib/bpf/libbpf.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 7c74342bb6680..5367bc8e52073 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -3191,11 +3191,11 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
Elf_Scn *scn;
Elf64_Shdr *sh;
- /* ELF section indices are 1-based, so allocate +1 element to keep
- * indexing simple. Also include 0th invalid section into sec_cnt for
- * simpler and more traditional iteration logic.
+ /* ELF section indices are 0-based, but sec #0 is special "invalid"
+ * section. e_shnum does include sec #0, so e_shnum is the necessary
+ * size of an array to keep all the sections.
*/
- obj->efile.sec_cnt = 1 + obj->efile.ehdr->e_shnum;
+ obj->efile.sec_cnt = obj->efile.ehdr->e_shnum;
obj->efile.secs = calloc(obj->efile.sec_cnt, sizeof(*obj->efile.secs));
if (!obj->efile.secs)
return -ENOMEM;
--
2.34.1
