Commit c08455de authored Nov 01, 2021 by Martin KaFai Lau Committed by Daniel Borkmann Nov 03, 2021

selftests/bpf: Verifier test on refill from a smaller spill

This patch adds a verifier test to ensure the verifier can read 8 bytes
from the stack after two 32bit write at fp-4 and fp-8. The test is similar
to the reported case from bcc [0].

  [0] https://github.com/iovisor/bcc/pull/3683



Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211102064541.316414-1-kafai@fb.com

parent f30d4968

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

+17 −0

Original line number	Diff line number	Diff line
		@@ -265,3 +265,20 @@
		.result = ACCEPT,
		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
		},
		{
		"Spill a u32 scalar at fp-4 and then at fp-8",
		.insns = {
		/* r4 = 4321 */
		BPF_MOV32_IMM(BPF_REG_4, 4321),
		/* (u32 )(r10 -4) = r4 */
		BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_4, -4),
		/* (u32 )(r10 -8) = r4 */
		BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_4, -8),
		/* r4 = (u64 )(r10 -8) */
		BPF_LDX_MEM(BPF_DW, BPF_REG_4, BPF_REG_10, -8),
		BPF_MOV64_IMM(BPF_REG_0, 0),
		BPF_EXIT_INSN(),
		},
		.result = ACCEPT,
		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
		},