From 27a0f3635d862919dd7e5e93e19f3f5d1b240e57 Mon Sep 17 00:00:00 2001 From: Jiayuan Chen Date: Wed, 1 Jul 2026 15:14:22 +0800 Subject: [PATCH] selftests/bpf: Fix test_maps sockmap failure test_maps fails in the sockmap test because sockmap_verdict_prog.c drops the packet when the first 8 bytes are not directly accessible: if (data + 8 > data_end) return SK_DROP; The blamed commit removed bpf_skb_pull_data() from the stream parser program so that the parser no longer modifies the skb. That was needed, but it also removed an implicit side effect: bpf_skb_pull_data() linearized enough of the skb for later direct packet access. In this test, the send side goes through the sockmap SK_MSG path. The skb can have skb->len == 20 while its linear area is empty, so the verdict program sees data == data_end and drops the packet even though the payload length is sufficient. Keep the parser read-only, and pull the first 8 bytes in the verdict program before reading or writing them. Reload data/data_end after bpf_skb_pull_data() as required. Fixes: 22a0cc10dacb ("selftests/bpf: don't modify the skb in the strparser parser prog") Reported-by: Ihor Solodrai Signed-off-by: Jiayuan Chen Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20260701071501.39628-1-jiayuan.chen@linux.dev Closes: https://lore.kernel.org/bpf/e3a91acd-2b4d-4e93-a3bb-a0e9ee5ede0f@linux.dev/ --- .../selftests/bpf/progs/sockmap_verdict_prog.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/bpf/progs/sockmap_verdict_prog.c b/tools/testing/selftests/bpf/progs/sockmap_verdict_prog.c index 0660f29dca95..3177bc5b733a 100644 --- a/tools/testing/selftests/bpf/progs/sockmap_verdict_prog.c +++ b/tools/testing/selftests/bpf/progs/sockmap_verdict_prog.c @@ -44,8 +44,18 @@ int bpf_prog2(struct __sk_buff *skb) __sink(lport); __sink(rport); - if (data + 8 > data_end) - return SK_DROP; + if (data + 8 > data_end) { + if (bpf_skb_pull_data(skb, 8)) + return SK_DROP; + + data = (void *)(long)skb->data; + data_end = (void *)(long)skb->data_end; + + if (data + 8 > data_end) + return SK_DROP; + + d = data; + } map = d[0]; sk = d[1];