laptop-kernel/tools/testing/selftests/bpf/prog_tests/test_map_uninit.c, branch masterLinux kernel tree for laptophttps://git.zx2c4.com/laptop-kernel/atom/tools/testing/selftests/bpf/prog_tests/test_map_uninit.c?h=master2026-07-01T18:27:37Zselftests/bpf: Verify no non-zeroed kernel heap memory exposure2026-07-01T18:27:37ZLeon Hwangleon.hwang@linux.dev2026-06-24T15:51:15Zurn:sha1:163944262f8646bf3a1eec557b6aff1f38582a9f
When lookup element from those per-CPU maps, which have special field
in their values and their value size is not equal to roundup(value_sz, 8),
the padding size of temporary non-zeroed kernel heap memory allocated by
kvmalloc should not be exposed to user space.
Without the fix:
test_map_uninit_mem_exposure:FAIL:zeroed tail bytes unexpected memory mismatch
actual:
2B 2B 2B 2B
expected:
00 00 00 00
Assisted-by: Codex:gpt-5.5
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20260624155115.85196-3-leon.hwang@linux.dev