From: John Fastabend Date: Thu, 21 May 2020 20:08:06 +0000 (-0700) Subject: bpf: Selftests, verifier case for non null pointer map value branch X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=f9b16ec0eeb75337aef38954a4066e6eecd7cfe5;p=linux.git bpf: Selftests, verifier case for non null pointer map value branch When we have pointer type that is known to be non-null we only follow the non-null branch. This adds tests to cover the map_value pointer returned from a map lookup. To force an error if both branches are followed we do an ALU op on R10. Signed-off-by: John Fastabend Signed-off-by: Alexei Starovoitov Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/159009168650.6313.7434084136067263554.stgit@john-Precision-5820-Tower --- diff --git a/tools/testing/selftests/bpf/verifier/value_or_null.c b/tools/testing/selftests/bpf/verifier/value_or_null.c index 860d4a71cd83a..3ecb70a3d9397 100644 --- a/tools/testing/selftests/bpf/verifier/value_or_null.c +++ b/tools/testing/selftests/bpf/verifier/value_or_null.c @@ -150,3 +150,22 @@ .result_unpriv = REJECT, .flags = F_NEEDS_EFFICIENT_UNALIGNED_ACCESS, }, +{ + "map lookup and null branch prediction", + .insns = { + BPF_MOV64_IMM(BPF_REG_1, 10), + BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_1, -8), + BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8), + BPF_LD_MAP_FD(BPF_REG_1, 0), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), + BPF_MOV64_REG(BPF_REG_6, BPF_REG_0), + BPF_JMP_IMM(BPF_JEQ, BPF_REG_6, 0, 2), + BPF_JMP_IMM(BPF_JNE, BPF_REG_6, 0, 1), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_10, 10), + BPF_EXIT_INSN(), + }, + .fixup_map_hash_8b = { 4 }, + .prog_type = BPF_PROG_TYPE_SCHED_CLS, + .result = ACCEPT, +},