bpf, test: fix ld_abs + vlan push/pop stress test
BugLink: https://bugs.launchpad.net/bugs/1879752 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: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> (cherry picked from commit 0d906b1e) Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com> Acked-by: Po-Hsu Lin <po-hsu.lin@canonical.com> Acked-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
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