netdev - [PATCH bpf-next 1/4] tools: libbpf: handle NULL program gracefully in bpf_program__nth

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Date:   Thu, 26 Jul 2018 14:32:18 -0700
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     alexei.starovoitov@...il.com, daniel@...earbox.net
Cc:     oss-drivers@...ronome.com, netdev@...r.kernel.org,
        Jakub Kicinski <jakub.kicinski@...ronome.com>
Subject: [PATCH bpf-next 1/4] tools: libbpf: handle NULL program gracefully in bpf_program__nth_fd()

bpf_map__fd() handles NULL map gracefully and returns -EINVAL.
bpf_program__fd() and bpf_program__nth_fd() crash in this case.
Make the behaviour more consistent by validating prog pointer
as well.

Signed-off-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@...ronome.com>
---
 tools/lib/bpf/libbpf.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 955f8eafbf41..afa9860db755 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1991,6 +1991,9 @@ int bpf_program__nth_fd(struct bpf_program *prog, int n)
 {
 	int fd;
 
+	if (!prog)
+		return -EINVAL;
+
 	if (n >= prog->instances.nr || n < 0) {
 		pr_warning("Can't get the %dth fd from program %s: only %d instances\n",
 			   n, prog->section_name, prog->instances.nr);
-- 
2.17.1