From: Wei Fu <fuweid89@gmail.com>
Date: Sat, 8 Jan 2022 16:40:08 +0800
Subject: bpftool: Only set obj->skeleton on complete success
Patch-mainline: v5.18-rc1
Git-commit: 0991f6a38f576aa9a5e34713e23c998a3310d4d0
References: jsc#PED-1377

After `bpftool gen skeleton`, the ${bpf_app}.skel.h will provide that
${bpf_app_name}__open helper to load bpf. If there is some error
like ENOMEM, the ${bpf_app_name}__open will rollback(free) the allocated
object, including `bpf_object_skeleton`.

Since the ${bpf_app_name}__create_skeleton set the obj->skeleton first
and not rollback it when error, it will cause double-free in
${bpf_app_name}__destory at ${bpf_app_name}__open. Therefore, we should
set the obj->skeleton before return 0;

Fixes: 5dc7a8b21144 ("bpftool, selftests/bpf: Embed object file inside skeleton")
Signed-off-by: Wei Fu <fuweid89@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220108084008.1053111-1-fuweid89@gmail.com
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
 tools/bpf/bpftool/gen.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/tools/bpf/bpftool/gen.c
+++ b/tools/bpf/bpftool/gen.c
@@ -924,7 +924,6 @@ static int do_skeleton(int argc, char **
 			s = (struct bpf_object_skeleton *)calloc(1, sizeof(*s));\n\
 			if (!s)						    \n\
 				goto err;				    \n\
-			obj->skeleton = s;				    \n\
 									    \n\
 			s->sz = sizeof(*s);				    \n\
 			s->name = \"%1$s\";				    \n\
@@ -997,6 +996,7 @@ static int do_skeleton(int argc, char **
 									    \n\
 			s->data = (void *)%2$s__elf_bytes(&s->data_sz);	    \n\
 									    \n\
+			obj->skeleton = s;				    \n\
 			return 0;					    \n\
 		err:							    \n\
 			bpf_object__destroy_skeleton(s);		    \n\