From 73c4936f916de73fa3faec204a4deb37c25e18c1 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Fri, 1 Jul 2022 14:47:26 +0200 Subject: [PATCH] bpf, selftests: Add verifier test case for imm=0,umin=0,umax=1 scalar Add a test case to trigger the constant scalar issue which leaves the register in scalar(imm=0,umin=0,umax=1,var_off=(0x0; 0x0)) state. Make use of dead code elimination, so that we can see the verifier bailing out on unfixed kernels. For the condition, we use jle given it checks on umax bound. Before: # ./test_verifier 743 #743/p jump & dead code elimination FAIL Failed to load prog 'Permission denied'! R4 !read_ok verification time 11 usec stack depth 0 processed 13 insns (limit 1000000) max_states_per_insn 0 total_states 1 peak_states 1 mark_read 1 Summary: 0 PASSED, 0 SKIPPED, 1 FAILED After: # ./test_verifier 743 #743/p jump & dead code elimination OK Summary: 1 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Daniel Borkmann Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20220701124727.11153-3-daniel@iogearbox.net --- tools/testing/selftests/bpf/verifier/jump.c | 22 +++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/tools/testing/selftests/bpf/verifier/jump.c b/tools/testing/selftests/bpf/verifier/jump.c index 6f951d1ff0a4..497fe17d2eaf 100644 --- a/tools/testing/selftests/bpf/verifier/jump.c +++ b/tools/testing/selftests/bpf/verifier/jump.c @@ -373,3 +373,25 @@ .result = ACCEPT, .retval = 3, }, +{ + "jump & dead code elimination", + .insns = { + BPF_MOV64_IMM(BPF_REG_0, 1), + BPF_MOV64_IMM(BPF_REG_3, 0), + BPF_ALU64_IMM(BPF_NEG, BPF_REG_3, 0), + BPF_ALU64_IMM(BPF_NEG, BPF_REG_3, 0), + BPF_ALU64_IMM(BPF_OR, BPF_REG_3, 32767), + BPF_JMP_IMM(BPF_JSGE, BPF_REG_3, 0, 1), + BPF_EXIT_INSN(), + BPF_JMP_IMM(BPF_JSLE, BPF_REG_3, 0x8000, 1), + BPF_EXIT_INSN(), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_3, -32767), + BPF_MOV64_IMM(BPF_REG_0, 2), + BPF_JMP_IMM(BPF_JLE, BPF_REG_3, 0, 1), + BPF_MOV64_REG(BPF_REG_0, BPF_REG_4), + BPF_EXIT_INSN(), + }, + .prog_type = BPF_PROG_TYPE_SCHED_CLS, + .result = ACCEPT, + .retval = 2, +},