From: Andrii Nakryiko <andriin@fb.com>
Date: Mon, 28 Oct 2019 16:37:27 -0700
Subject: libbpf: Fix off-by-one error in ELF sanity check
Patch-mainline: Queued in subsystem maintainer repository
Git-repo: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Git-commit: d3a3aa0c59e83d8c13a758128b10dd459ce0d866
References: bsc#1155518

libbpf's bpf_object__elf_collect() does simple sanity check after iterating
over all ELF sections, if checks that .strtab index is correct. Unfortunately,
due to section indices being 1-based, the check breaks for cases when .strtab
ends up being the very last section in ELF.

Fixes: 77ba9a5b48a7 ("tools lib bpf: Fetch map names from correct strtab")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20191028233727.1286699-1-andriin@fb.com
Acked-by: Gary Lin <glin@suse.com>
---
 tools/lib/bpf/libbpf.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1645,7 +1645,7 @@ static int bpf_object__elf_collect(struc
 		}
 	}
 
-	if (!obj->efile.strtabidx || obj->efile.strtabidx >= idx) {
+	if (!obj->efile.strtabidx || obj->efile.strtabidx > idx) {
 		pr_warning("Corrupted ELF file: index of strtab invalid\n");
 		return -LIBBPF_ERRNO__FORMAT;
 	}