[PATCH bpf-next] libbpf: avoid mmap for size 0 sections

[David Faust <david.faust@oracle.com>]

When populating maps in bpf_object__init_global_data_maps(), recognized
sections with no data (e.g. a .bss with size 0) lead to an mmap of 0
bytes which fails with EINVAL.

Add a check to skip mapping sections which are present, but empty.

Signed-off-by: David Faust <david.faust@oracle.com>
---
 tools/lib/bpf/libbpf.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index b01fe01b0761..4e7ceb4f5a27 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1642,6 +1642,10 @@ static int bpf_object__init_global_data_maps(struct bpf_object *obj)
 	for (sec_idx = 1; sec_idx < obj->efile.sec_cnt; sec_idx++) {
 		sec_desc = &obj->efile.secs[sec_idx];
 
+		/* Skip recognized sections with size 0. */
+		if (sec_desc->data && sec_desc->data->d_size == 0)
+		  continue;
+
 		switch (sec_desc->sec_type) {
 		case SEC_DATA:
 			sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
-- 
2.36.1