From 4a11678f683814df82fca9018d964771e02d7e6d Mon Sep 17 00:00:00 2001 From: Felix Maurer Date: Wed, 9 Feb 2022 16:55:26 +0100 Subject: [PATCH] bpf: Do not try bpf_msg_push_data with len 0 If bpf_msg_push_data() is called with len 0 (as it happens during selftests/bpf/test_sockmap), we do not need to do anything and can return early. Calling bpf_msg_push_data() with len 0 previously lead to a wrong ENOMEM error: we later called get_order(copy + len); if len was 0, copy + len was also often 0 and get_order() returned some undefined value (at the moment 52). alloc_pages() caught that and failed, but then bpf_msg_push_data() returned ENOMEM. This was wrong because we are most probably not out of memory and actually do not need any additional memory. Fixes: 6fff607e2f14b ("bpf: sk_msg program helper bpf_msg_push_data") Signed-off-by: Felix Maurer Signed-off-by: Daniel Borkmann Acked-by: Yonghong Song Acked-by: John Fastabend Link: https://lore.kernel.org/bpf/df69012695c7094ccb1943ca02b4920db3537466.1644421921.git.fmaurer@redhat.com --- net/core/filter.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/core/filter.c b/net/core/filter.c index 4603b7cd3cd1..9eb785842258 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -2710,6 +2710,9 @@ BPF_CALL_4(bpf_msg_push_data, struct sk_msg *, msg, u32, start, if (unlikely(flags)) return -EINVAL; + if (unlikely(len == 0)) + return 0; + /* First find the starting scatterlist element */ i = msg->sg.start; do { -- 2.11.0