[PATCH bpf v1 1/1] bpf: Fix sk_local_storage diag dumping uninitialized special fields

[Amery Hung <ameryhung@gmail.com>]

Call check_and_init_map_value() after the copy_map_value() to zero out
special field regions. diag_get() copies sk_local_storage map values
into a netlink message using copy_map_value{_locked}(), which
intentionally skip special fields. However, the destination buffer from
nla_reserve_64bit() is not zeroed and the skipped regions contain
uninitialized skb data can be sent to userspace.

Fixes: 1ed4d92458a9 ("bpf: INET_DIAG support in bpf_sk_storage")
Signed-off-by: Amery Hung <ameryhung@gmail.com>
---
 net/core/bpf_sk_storage.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/core/bpf_sk_storage.c b/net/core/bpf_sk_storage.c
index 14eb7812bda4..b50d26a542ed 100644
--- a/net/core/bpf_sk_storage.c
+++ b/net/core/bpf_sk_storage.c
@@ -558,6 +558,7 @@ static int diag_get(struct bpf_local_storage_data *sdata, struct sk_buff *skb)
 				      sdata->data, true);
 	else
 		copy_map_value(&smap->map, nla_data(nla_value), sdata->data);
+	check_and_init_map_value(&smap->map, nla_data(nla_value));
 
 	nla_nest_end(skb, nla_stg);
 	return 0;
-- 
2.52.0