From: Felix Maurer fmaurer@redhat.com
commit 4a11678f683814df82fca9018d964771e02d7e6d upstream.
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 fmaurer@redhat.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Acked-by: Yonghong Song yhs@fb.com Acked-by: John Fastabend john.fastabend@gmail.com Link: https://lore.kernel.org/bpf/df69012695c7094ccb1943ca02b4920db3537466.1644421... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/core/filter.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/net/core/filter.c +++ b/net/core/filter.c @@ -2730,6 +2730,9 @@ BPF_CALL_4(bpf_msg_push_data, struct sk_ if (unlikely(flags)) return -EINVAL;
+ if (unlikely(len == 0)) + return 0; + /* First find the starting scatterlist element */ i = msg->sg.start; do {