[PATCH bpf-next] bpf: Fix security_bpf_map_create error handling

[Daniel Borkmann <daniel@iogearbox.net>]

Commit 5816bf4273ed ("lsm,selinux: Add LSM blob support for BPF objects")
made the LSM hook wrappers for BPF object creation clean up the LSM
state internally upon denial, e.g. security_bpf_map_create() internally
calls security_bpf_map_free() when the bpf_map_create hook returns an
error. map_create() however still routes a denial to its free_map_sec
label, which invokes security_bpf_map_free() a second time, so the
bpf_map_free hook fires twice for a single denied map.

In-tree LSMs are unaffected in practice since the blob kfree() inside
security_bpf_map_free() is NULL-safe and idempotent and none of them
implement bpf_map_free, but a BPF LSM program attached to that hook
observes double invocations. Route the denial to free_map instead.

Fixes: 5816bf4273ed ("lsm,selinux: Add LSM blob support for BPF objects")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
---
 kernel/bpf/syscall.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 358f2b0ce2bd..0ff9e3aa293d 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1649,7 +1649,7 @@ static int map_create(union bpf_attr *attr, bpfptr_t uattr, struct bpf_common_at
 
 	err = security_bpf_map_create(map, attr, token, uattr.is_kernel);
 	if (err)
-		goto free_map_sec;
+		goto free_map;
 
 	err = bpf_map_alloc_id(map);
 	if (err)
-- 
2.43.0