From: Daniel Borkmann <daniel@iogearbox.net>
Date: Fri, 1 Jul 2022 14:47:27 +0200
Subject: bpf, selftests: Add verifier test case for jmp32's jeq/jne
Patch-mainline: v5.19-rc6
Git-commit: a49b8ce7306cf8031361a6a4f7f6bc7a775a39c8
References: jsc#PED-1377
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 <daniel@iogearbox.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220701124727.11153-4-daniel@iogearbox.net
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
tools/testing/selftests/bpf/verifier/jmp32.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
--- 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,
+},