selftests/bpf: add tests for PTR_TO_FLOW_KEYS offset bounds

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Add verifier tests covering pointer arithmetic on a PTR_TO_FLOW_KEYS
register. This covers the bpf-next regression where an out-of-bounds
constant offset introduced as flow_keys += K and then dereferenced at
insn->off 0 was accepted, while the equivalent flow_keys + K direct offset
was rejected.

The tests check that in-bounds constant arithmetic on the keys pointer is
still accepted, out-of-bounds constant arithmetic is rejected for both read
and write, and a truly varying offset from bpf_get_prandom_u32() remains
rejected by the existing PTR_TO_FLOW_KEYS pointer arithmetic rules.

Signed-off-by: Nuoqi Gui <gnq25@mails.tsinghua.edu.cn>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260606-c3-01-v3-v3-2-97c51f592f15@mails.tsinghua.edu.cn
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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Nuoqi Gui 2026-06-06 18:50:38 +08:00 • committed by Alexei Starovoitov

parent 37363191cb

commit 3ce6b42458

2 changed files with 99 additions and 0 deletions

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tools/testing/selftests/bpf/prog_tests/verifier.c

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97

tools/testing/selftests/bpf/progs/verifier_flow_keys.c

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