From c565269d06e982cd947cc5e5ef020274c9c03c11 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Thu, 9 Aug 2018 08:55:19 -0700 Subject: [PATCH] bpf: fix bpffs non-array map seq_show issue [ Upstream commit dc1508a579e682a1e5f1ed0753390e0aa7c23a97 ] In function map_seq_next() of kernel/bpf/inode.c, the first key will be the "0" regardless of the map type. This works for array. But for hash type, if it happens key "0" is in the map, the bpffs map show will miss some items if the key "0" is not the first element of the first bucket. This patch fixed the issue by guaranteeing to get the first element, if the seq_show is just started, by passing NULL pointer key to map_get_next_key() callback. This way, no missing elements will occur for bpffs hash table show even if key "0" is in the map. Fixes: a26ca7c982cb5 ("bpf: btf: Add pretty print support to the basic arraymap") Acked-by: Alexei Starovoitov Signed-off-by: Yonghong Song Signed-off-by: Daniel Borkmann Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- kernel/bpf/inode.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c index 76efe9a183f5..fc5b103512e7 100644 --- a/kernel/bpf/inode.c +++ b/kernel/bpf/inode.c @@ -196,19 +196,21 @@ static void *map_seq_next(struct seq_file *m, void *v, loff_t *pos) { struct bpf_map *map = seq_file_to_map(m); void *key = map_iter(m)->key; + void *prev_key; if (map_iter(m)->done) return NULL; if (unlikely(v == SEQ_START_TOKEN)) - goto done; + prev_key = NULL; + else + prev_key = key; - if (map->ops->map_get_next_key(map, key, key)) { + if (map->ops->map_get_next_key(map, prev_key, key)) { map_iter(m)->done = true; return NULL; } -done: ++(*pos); return key; }