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Yauheni KaliutaandGreg Kroah-Hartman
4d2cdb2ded
commit6185266c5aupstream. The verifier test labelled "valid read map access into a read-only array 2" calls the bpf_csum_diff() helper and checks its return value. However, architecture implementations of csum_partial() (which is what the helper uses) differ in whether they fold the return value to 16 bit or not. For example, x86 version has ... if (unlikely(odd)) { result = from32to16(result); result = ((result >> 8) & 0xff) | ((result & 0xff) << 8); } ... while generic lib/checksum.c does: result = from32to16(result); if (odd) result = ((result >> 8) & 0xff) | ((result & 0xff) << 8); This makes the helper return different values on different architectures, breaking the test on non-x86. To fix this, add an additional instruction to always mask the return value to 16 bits, and update the expected return value accordingly. Fixes:fb2abb73e5("bpf, selftest: test {rd, wr}only flags and direct value access") Signed-off-by: Yauheni Kaliuta <yauheni.kaliuta@redhat.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20210228103017.320240-1-yauheni.kaliuta@redhat.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>