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

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[ Upstream commit 03e601f48b2da6fb44d0f7b86957a8f6bacfb347 ]

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
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Toke Høiland-Jørgensen 2021-09-01 13:48:12 +02:00 committed by Greg Kroah-Hartman
parent 11080de0a7
commit 9fc0420864
1 changed files with 6 additions and 0 deletions
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6
tools/lib/bpf/libbpf.c
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@ -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++;