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Florent Revest authored
The BPF program for the snprintf selftest runs on all syscall entries. On busy multicore systems this can cause concurrency issues. For example it was observed that sometimes the userspace part of the test reads " 4 0000" instead of " 4 000" (extra '0' at the end) which seems to happen just before snprintf on another core sets end[-1] = '\0'. This patch adds a pid filter to the test to ensure that no bpf_snprintf() will write over the test's output buffers while the userspace reads the values. Fixes: c2e39c6b ("selftests/bpf: Add a series of tests for bpf_snprintf") Reported-by:
Andrii Nakryiko <andrii@kernel.org> Signed-off-by:
Florent Revest <revest@chromium.org> Signed-off-by:
Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210428152501.1024509-1-revest@chromium.org
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