From a49b8ce7306cf8031361a6a4f7f6bc7a775a39c8 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Fri, 1 Jul 2022 14:47:27 +0200 Subject: [PATCH] bpf, selftests: Add verifier test case for jmp32's jeq/jne Add a test case to trigger the verifier's incorrect conclusion in the case of jmp32's jeq/jne. Also here, make use of dead code elimination, so that we can see the verifier bailing out on unfixed kernels. Before: # ./test_verifier 724 #724/p jeq32/jne32: bounds checking FAIL Failed to load prog 'Permission denied'! R4 !read_ok verification time 8 usec stack depth 0 processed 8 insns (limit 1000000) max_states_per_insn 0 total_states 1 peak_states 1 mark_read 0 Summary: 0 PASSED, 0 SKIPPED, 1 FAILED After: # ./test_verifier 724 #724/p jeq32/jne32: bounds checking OK Summary: 1 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Daniel Borkmann Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20220701124727.11153-4-daniel@iogearbox.net --- tools/testing/selftests/bpf/verifier/jmp32.c | 21 ++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/tools/testing/selftests/bpf/verifier/jmp32.c b/tools/testing/selftests/bpf/verifier/jmp32.c index 6ddc418fdfaf..1a27a6210554 100644 --- a/tools/testing/selftests/bpf/verifier/jmp32.c +++ b/tools/testing/selftests/bpf/verifier/jmp32.c @@ -864,3 +864,24 @@ .result = ACCEPT, .flags = F_NEEDS_EFFICIENT_UNALIGNED_ACCESS, }, +{ + "jeq32/jne32: bounds checking", + .insns = { + BPF_MOV64_IMM(BPF_REG_6, 563), + BPF_MOV64_IMM(BPF_REG_2, 0), + BPF_ALU64_IMM(BPF_NEG, BPF_REG_2, 0), + BPF_ALU64_IMM(BPF_NEG, BPF_REG_2, 0), + BPF_ALU32_REG(BPF_OR, BPF_REG_2, BPF_REG_6), + BPF_JMP32_IMM(BPF_JNE, BPF_REG_2, 8, 5), + BPF_JMP_IMM(BPF_JSGE, BPF_REG_2, 500, 2), + BPF_MOV64_IMM(BPF_REG_0, 2), + BPF_EXIT_INSN(), + BPF_MOV64_REG(BPF_REG_0, BPF_REG_4), + BPF_EXIT_INSN(), + BPF_MOV64_IMM(BPF_REG_0, 1), + BPF_EXIT_INSN(), + }, + .prog_type = BPF_PROG_TYPE_SCHED_CLS, + .result = ACCEPT, + .retval = 1, +},