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* [PATCH bpf v2] libbpf: don't crash on object files with no symbol tables
@ 2021-09-01 11:48 Toke Høiland-Jørgensen
  2021-09-08  0:30 ` Andrii Nakryiko
  0 siblings, 1 reply; 2+ messages in thread
From: Toke Høiland-Jørgensen @ 2021-09-01 11:48 UTC (permalink / raw)
  To: Andrii Nakryiko; +Cc: bpf, netdev, Toke Høiland-Jørgensen

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>
---
 tools/lib/bpf/libbpf.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 6f5e2757bb3c..997060182cef 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -2990,6 +2990,12 @@ 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++;
-- 
2.33.0


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2021-09-01 11:48 [PATCH bpf v2] libbpf: don't crash on object files with no symbol tables Toke Høiland-Jørgensen
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