bpf: Deref map in BPF_PROG_BIND_MAP when it's already used

We are missing a deref for the case when we are doing BPF_PROG_BIND_MAP on a map that's being already held by the program. There is 'if (ret) bpf_map_put(map)' below which doesn't trigger because we don't consider this an error. Let's add missing bpf_map_put() for this specific condition. Fixes: ef15314 ("bpf: Add BPF_PROG_BIND_MAP syscall") Reported-by: Alexei Starovoitov <[email protected]> Signed-off-by: Stanislav Fomichev <[email protected]> Signed-off-by: Alexei Starovoitov <[email protected]> Acked-by: Andrii Nakryiko <[email protected]> Link: https://lore.kernel.org/bpf/[email protected]
dabrace · Oct 3, 2020 · 1028ae4 · 1028ae4
1 parent fb91db0
commit 1028ae4
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
@@ -4323,8 +4323,10 @@ static int bpf_prog_bind_map(union bpf_attr *attr)
 	used_maps_old = prog->aux->used_maps;
 
 	for (i = 0; i < prog->aux->used_map_cnt; i++)
-		if (used_maps_old[i] == map)
+		if (used_maps_old[i] == map) {
+			bpf_map_put(map);
 			goto out_unlock;
+		}
 
 	used_maps_new = kmalloc_array(prog->aux->used_map_cnt + 1,
 				      sizeof(used_maps_new[0]),