bpf_object__btf() can return a NULL value.  If bpf_object__btf returns
null, do not progress through codegen_asserts(). This avoids a null ptr
dereference at the call btf__type_cnt() in the function find_type_for_map()

Signed-off-by: Michael Mullin <masmullin@gmail.com>
---
 tools/bpf/bpftool/gen.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c
index 4c9477ff748d..f158dc1c2149 100644
--- a/tools/bpf/bpftool/gen.c
+++ b/tools/bpf/bpftool/gen.c
@@ -474,6 +474,9 @@ static void codegen_asserts(struct bpf_object *obj, const char *obj_name)
 	const struct btf_type *sec;
 	char map_ident[256], var_ident[256];
 
+	if (!btf)
+		return;
+
 	codegen("\
 		\n\
 		__attribute__((unused)) static void			    \n\
-- 
2.36.1

Hello:

This patch was applied to bpf/bpf-next.git (master)
by Andrii Nakryiko <andrii@kernel.org>:

On Mon, 23 May 2022 15:49:17 -0400 you wrote:
> bpf_object__btf() can return a NULL value.  If bpf_object__btf returns
> null, do not progress through codegen_asserts(). This avoids a null ptr
> dereference at the call btf__type_cnt() in the function find_type_for_map()
> 
> Signed-off-by: Michael Mullin <masmullin@gmail.com>
> ---
>  tools/bpf/bpftool/gen.c | 3 +++
>  1 file changed, 3 insertions(+)

Here is the summary with links:
  - Check for NULL ptr of btf in codegen_asserts
    https://git.kernel.org/bpf/bpf-next/c/d992a11f1171

You are awesome, thank you!
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