Commit 0d906b1e authored by Daniel Borkmann's avatar Daniel Borkmann Committed by David S. Miller

bpf, test: fix ld_abs + vlan push/pop stress test

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>
parent fcd91dd4
......@@ -4831,7 +4831,7 @@ static struct bpf_test tests[] = {
{ },
INTERNAL,
{ 0x34 },
{ { 1, 0xbef } },
{ { ETH_HLEN, 0xbef } },
.fill_helper = bpf_fill_ld_abs_vlan_push_pop,
},
/*
......
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