• Daniel Borkmann's avatar
    bpf, test: fix ld_abs + vlan push/pop stress test · 0d906b1e
    Daniel Borkmann authored
    After commit 636c2628 ("net: skbuff: Remove errornous length
    validation in skb_vlan_pop()") mentioned test case stopped working,
    throwing a -12 (ENOMEM) return code. The issue however is not due to
    636c2628, but rather due to a buggy test case that got uncovered
    from the change in behaviour in 636c2628.
    The data_size of that test case for the skb was set to 1. In the
    bpf_fill_ld_abs_vlan_push_pop() handler bpf insns are generated that
    loop with: reading skb data, pushing 68 tags, reading skb data,
    popping 68 tags, reading skb data, etc, in order to force a skb
    expansion and thus trigger that JITs recache skb->data. Problem is
    that initial data_size is too small.
    While before 636c2628, the test silently bailed out due to the
    skb->len < VLAN_ETH_HLEN check with returning 0, and now throwing an
    error from failing skb_ensure_writable(). Set at least minimum of
    ETH_HLEN as an initial length so that on first push of data, equivalent
    pop will succeed.
    Fixes: 4d9c5c53 ("test_bpf: add bpf_skb_vlan_push/pop() tests")
    Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
    Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
test_bpf.c 134 KB