selftests/bpf: Exercise negative optlen in cgroup getsockopt hook

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Add a cgroup getsockopt selftest that sets ctx->optlen to -1. Use
TCP_ZEROCOPY_RECEIVE to exercise the kernel-buffer getsockopt hook.

The userspace-visible result is -EFAULT on both patched and unpatched
kernels, so the return value alone cannot distinguish the bug. The test
still exercises the kernel-buffer getsockopt path with a negative
ctx->optlen, which reproduces the hardened usercopy warning on unpatched
kernels.

Signed-off-by: Junseo Lim <zirajs7@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/4dbdcda23b2f2be06c5659f8102cd6bd036825b3.1786448307.git.zirajs7@gmail.com

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Junseo Lim 2026-08-11 23:19:08 +09:00 • committed by Daniel Borkmann

parent 1b5aacd5b2

commit 6b0835ac79

1 changed files with 22 additions and 0 deletions

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

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