[PATCH] selftests/bpf: Fix count write in testapp_xdp_metadata_copy()
From: Ricardo B. Marlière <hidden>
Date: 2025-08-29 19:33:56
Also in:
bpf, linux-kselftest, lkml
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [selftests] (test runners & infrastructure), kernel selftest framework, the rest, xdp sockets (af_xdp) · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Shuah Khan, Linus Torvalds, Magnus Karlsson, Maciej Fijalkowski
Commit 4b302092553c ("selftests/xsk: Add tail adjustment tests and support
check") added a new global to xsk_xdp_progs.c, but left out the access in
the testapp_xdp_metadata_copy() function. Since bpf_map_update_elem() will
write to the whole bss section, it gets truncated. Fix by writing to
skel_rx->bss->count directly.
Fixes: 4b302092553c ("selftests/xsk: Add tail adjustment tests and support check")
Signed-off-by: Ricardo B. Marlière <redacted>
---
tools/testing/selftests/bpf/xskxceiver.c | 14 +-------------
1 file changed, 1 insertion(+), 13 deletions(-)
diff --git a/tools/testing/selftests/bpf/xskxceiver.c b/tools/testing/selftests/bpf/xskxceiver.c
index a29de0713f19f05ef49a52e3824bb58a30565e87..352adc8df2d1cd777c823c5a89f1720ee043f342 100644
--- a/tools/testing/selftests/bpf/xskxceiver.c
+++ b/tools/testing/selftests/bpf/xskxceiver.c@@ -2276,25 +2276,13 @@ static int testapp_xdp_metadata_copy(struct test_spec *test) { struct xsk_xdp_progs *skel_rx = test->ifobj_rx->xdp_progs; struct xsk_xdp_progs *skel_tx = test->ifobj_tx->xdp_progs; - struct bpf_map *data_map; - int count = 0; - int key = 0; test_spec_set_xdp_prog(test, skel_rx->progs.xsk_xdp_populate_metadata, skel_tx->progs.xsk_xdp_populate_metadata, skel_rx->maps.xsk, skel_tx->maps.xsk); test->ifobj_rx->use_metadata = true; - data_map = bpf_object__find_map_by_name(skel_rx->obj, "xsk_xdp_.bss"); - if (!data_map || !bpf_map__is_internal(data_map)) { - ksft_print_msg("Error: could not find bss section of XDP program\n"); - return TEST_FAILURE; - } - - if (bpf_map_update_elem(bpf_map__fd(data_map), &key, &count, BPF_ANY)) { - ksft_print_msg("Error: could not update count element\n"); - return TEST_FAILURE; - } + skel_rx->bss->count = 0; return testapp_validate_traffic(test); }
--- base-commit: 5b6d6fe1ca7b712c74f78426bb23c465fd34b322 change-id: 20250829-selftests-bpf-xsk_regression_fix-674d292e4d2a Best regards, -- Ricardo B. Marlière [off-list ref]