From 3b4130418f62b0e7a4685cc2c03bb41c6cb8922d Mon Sep 17 00:00:00 2001
From: Martin KaFai Lau <kafai@fb.com>
Date: Mon, 13 Jan 2020 23:26:47 -0800
Subject: [PATCH] bpf: Fix seq_show for BPF_MAP_TYPE_STRUCT_OPS
Instead of using bpf_struct_ops_map_lookup_elem() which is
not implemented, bpf_struct_ops_map_seq_show_elem() should
also use bpf_struct_ops_map_sys_lookup_elem() which does
an inplace update to the value. The change allocates
a value to pass to bpf_struct_ops_map_sys_lookup_elem().
[root@arch-fb-vm1 bpf]# cat /sys/fs/bpf/dctcp
{{{1}},BPF_STRUCT_OPS_STATE_INUSE,{{00000000df93eebc,00000000df93eebc},0,2, ...
Fixes: 85d33df357b6 ("bpf: Introduce BPF_MAP_TYPE_STRUCT_OPS")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200114072647.3188298-1-kafai@fb.com
---
kernel/bpf/bpf_struct_ops.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
index ddf48f49914bf..8ad1c9ea26b28 100644
--- a/kernel/bpf/bpf_struct_ops.c
+++ b/kernel/bpf/bpf_struct_ops.c
@@ -496,14 +496,20 @@ static void bpf_struct_ops_map_seq_show_elem(struct bpf_map *map, void *key,
struct seq_file *m)
{
void *value;
+ int err;
- value = bpf_struct_ops_map_lookup_elem(map, key);
+ value = kmalloc(map->value_size, GFP_USER | __GFP_NOWARN);
if (!value)
return;
- btf_type_seq_show(btf_vmlinux, map->btf_vmlinux_value_type_id,
- value, m);
- seq_puts(m, "\n");
+ err = bpf_struct_ops_map_sys_lookup_elem(map, key, value);
+ if (!err) {
+ btf_type_seq_show(btf_vmlinux, map->btf_vmlinux_value_type_id,
+ value, m);
+ seq_puts(m, "\n");
+ }
+
+ kfree(value);
}
static void bpf_struct_ops_map_free(struct bpf_map *map)
--
2.39.5