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
This commit is contained in:
Martin KaFai Lau 2021-11-01 23:45:41 -07:00 committed by Daniel Borkmann
parent f30d4968e9
commit c08455dec5

View File

@ -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,
},