Commit 0d6988e1 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Alexei Starovoitov
Browse files

libbpf: Fix section counting logic 



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: 25bbbd7a ("libbpf: Remove assumptions about uniqueness of .rodata/.data/.bss maps")
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211103173213.1376990-5-andrii@kernel.org
parent 62554d52

tools/lib/bpf/libbpf.c

+4 −4
Original line number Diff line number Diff line
@@ -3190,11 +3190,11 @@ 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;