Re: [PATCH bpf] libbpf: don't crash on object files with no symbol tables
From: Andrii Nakryiko <hidden>
Date: 2021-08-31 22:46:08
Also in:
netdev
On Tue, Aug 31, 2021 at 9:58 AM Toke Høiland-Jørgensen [off-list ref] wrote:
quoted hunk ↗ jump to hunk
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. Add a check and return to avoid this. Fixes: 6245947c1b3c ("libbpf: Allow gaps in BPF program sections to support overriden weak functions") Signed-off-by: Toke Høiland-Jørgensen <redacted> --- tools/lib/bpf/libbpf.c | 3 +++ 1 file changed, 3 insertions(+)diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 6f5e2757bb3c..4cd102affeef 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c@@ -668,6 +668,9 @@ bpf_object__add_programs(struct bpf_object *obj, Elf_Data *sec_data, const char *name; GElf_Sym sym; + if (!symbols) + return -ENOENT; +
The more logical place to do this check is in bpf_object__elf_collect(). Can you add this there? We can also include helpful error message. But I'm also curious which Clang version is being used to cause no ELF symbols being generated?
progs = obj->programs;
nr_progs = obj->nr_programs;
nr_syms = symbols->d_size / sizeof(GElf_Sym);
--
2.33.0