Commit a49b8ce7 authored by Daniel Borkmann's avatar Daniel Borkmann Committed by Andrii Nakryiko
Browse files

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: default avatarDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220701124727.11153-4-daniel@iogearbox.net
parent 73c4936f

tools/testing/selftests/bpf/verifier/jmp32.c

+21 −0
Original line number Diff line number Diff line
@@ -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,

},