bpf_gen__prog_load() byte-swaps the program insns and the {func,line}_info and CO-RE relo blobs in place for cross-endian targets. The blob offsets come from add_data(), which returns 0 on failure: realloc_data_buf() either frees and NULLs gen->data_start (realloc OOM) or returns early on an already-latched gen->error, leaving a stale, possibly too-small buffer. Neither bswap site checked for this. With gen->swapped_endian set and a failed generation, "gen->data_start + off" becomes NULL + 0. Guard the same way via !gen->error so they are skipped once generation has failed. Fixes: 8ca3323dce43 ("libbpf: Support creating light skeleton of either endianness") Reported-by: sashiko Signed-off-by: Daniel Borkmann --- [ Addressing https://lore.kernel.org/bpf/030307d2-f065-4434-b746-4ef5349f6190@iogearbox.net/ ] tools/lib/bpf/gen_loader.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/tools/lib/bpf/gen_loader.c b/tools/lib/bpf/gen_loader.c index bcea21c3b7bb..fb4425cbffa3 100644 --- a/tools/lib/bpf/gen_loader.c +++ b/tools/lib/bpf/gen_loader.c @@ -1054,7 +1054,7 @@ void bpf_gen__prog_load(struct bpf_gen *gen, prog_idx, prog_type, insns_off, insn_cnt, license_off); /* convert blob insns to target endianness */ - if (gen->swapped_endian) { + if (gen->swapped_endian && !gen->error) { struct bpf_insn *insn = gen->data_start + insns_off; int i; @@ -1092,7 +1092,7 @@ void bpf_gen__prog_load(struct bpf_gen *gen, sizeof(struct bpf_core_relo)); /* convert all info blobs to target endianness */ - if (gen->swapped_endian) + if (gen->swapped_endian && !gen->error) info_blob_bswap(gen, func_info, line_info, core_relos, load_attr); libbpf_strlcpy(attr.prog_name, prog_name, sizeof(attr.prog_name)); -- 2.43.0