From: Toke Høiland-Jørgensen <toke@redhat.com>
Date: Wed, 1 Sep 2021 11:48:12 +0000 (+0200)
Subject: libbpf: Don't crash on object files with no symbol tables
X-Git-Tag: howlett/maple/20220722_2~1960^2~417^2~19
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=03e601f48b2da6fb44d0f7b86957a8f6bacfb347;p=users%2Fjedix%2Flinux-maple.git

libbpf: Don't crash on object files with no symbol tables

If libbpf encounters an ELF file that has been stripped of its symbol
table, it will crash in bpf_object__add_programs() when trying to
dereference the obj->efile.symbols pointer.

Fix this by erroring out of bpf_object__elf_collect() if it is not able
able to find the symbol table.

v2:
  - Move check into bpf_object__elf_collect() and add nice error message

Fixes: 6245947c1b3c ("libbpf: Allow gaps in BPF program sections to support overriden weak functions")
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210901114812.204720-1-toke@redhat.com
---

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 88d8825fc6f6..8f579c6666b2 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -2993,6 +2993,12 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
 		}
 	}
 
+	if (!obj->efile.symbols) {
+		pr_warn("elf: couldn't find symbol table in %s, stripped object file?\n",
+			obj->path);
+		return -ENOENT;
+	}
+
 	scn = NULL;
 	while ((scn = elf_nextscn(elf, scn)) != NULL) {
 		idx++;