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author | Yonghong Song <yonghong.song@linux.dev> | 2024-02-04 11:44:52 -0800 |
---|---|---|
committer | Andrii Nakryiko <andrii@kernel.org> | 2024-02-05 10:48:41 -0800 |
commit | 7e428638bd784fd9e8944bfbf11513520e141b91 (patch) | |
tree | bab39b99b5cc9453ae43dbc5a06df7c60072b2a4 /tools/testing/selftests/bpf/progs | |
parent | bpf: Remove an unnecessary check. (diff) | |
download | wireguard-linux-7e428638bd784fd9e8944bfbf11513520e141b91.tar.xz wireguard-linux-7e428638bd784fd9e8944bfbf11513520e141b91.zip |
selftests/bpf: Fix flaky test ptr_untrusted
Somehow recently I frequently hit the following test failure
with either ./test_progs or ./test_progs-cpuv4:
serial_test_ptr_untrusted:PASS:skel_open 0 nsec
serial_test_ptr_untrusted:PASS:lsm_attach 0 nsec
serial_test_ptr_untrusted:PASS:raw_tp_attach 0 nsec
serial_test_ptr_untrusted:FAIL:cmp_tp_name unexpected cmp_tp_name: actual -115 != expected 0
#182 ptr_untrusted:FAIL
Further investigation found the failure is due to
bpf_probe_read_user_str()
where reading user-level string attr->raw_tracepoint.name
is not successfully, most likely due to the
string itself still in disk and not populated into memory yet.
One solution is do a printf() call of the string before doing bpf
syscall which will force the raw_tracepoint.name into memory.
But I think a more robust solution is to use bpf_copy_from_user()
which is used in sleepable program and can tolerate page fault,
and the fix here used the latter approach.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240204194452.2785936-1-yonghong.song@linux.dev
Diffstat (limited to 'tools/testing/selftests/bpf/progs')
-rw-r--r-- | tools/testing/selftests/bpf/progs/test_ptr_untrusted.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/tools/testing/selftests/bpf/progs/test_ptr_untrusted.c b/tools/testing/selftests/bpf/progs/test_ptr_untrusted.c index 4bdd65b5aa2d..2fdc44e76624 100644 --- a/tools/testing/selftests/bpf/progs/test_ptr_untrusted.c +++ b/tools/testing/selftests/bpf/progs/test_ptr_untrusted.c @@ -6,13 +6,13 @@ char tp_name[128]; -SEC("lsm/bpf") +SEC("lsm.s/bpf") int BPF_PROG(lsm_run, int cmd, union bpf_attr *attr, unsigned int size) { switch (cmd) { case BPF_RAW_TRACEPOINT_OPEN: - bpf_probe_read_user_str(tp_name, sizeof(tp_name) - 1, - (void *)attr->raw_tracepoint.name); + bpf_copy_from_user(tp_name, sizeof(tp_name) - 1, + (void *)attr->raw_tracepoint.name); break; default: break; |