1 files changed, 66 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/verifier/var_off.c b/tools/testing/selftests/bpf/verifier/var_off.c
new file mode 100644
index 000000000000..1e536ff121a5
--- /dev/null
+++ b/tools/testing/selftests/bpf/verifier/var_off.c
@@ -0,0 +1,66 @@
+{
+	"variable-offset ctx access",
+	.insns = {
+	/* Get an unknown value */
+	BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 0),
+	/* Make it small and 4-byte aligned */
+	BPF_ALU64_IMM(BPF_AND, BPF_REG_2, 4),
+	/* add it to skb.  We now have either &skb->len or
+	 * &skb->pkt_type, but we don't know which
+	 */
+	BPF_ALU64_REG(BPF_ADD, BPF_REG_1, BPF_REG_2),
+	/* dereference it */
+	BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1, 0),
+	BPF_EXIT_INSN(),
+	},
+	.errstr = "variable ctx access var_off=(0x0; 0x4)",
+	.result = REJECT,
+	.prog_type = BPF_PROG_TYPE_LWT_IN,
+},
+{
+	"variable-offset stack access",
+	.insns = {
+	/* Fill the top 8 bytes of the stack */
+	BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
+	/* Get an unknown value */
+	BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 0),
+	/* Make it small and 4-byte aligned */
+	BPF_ALU64_IMM(BPF_AND, BPF_REG_2, 4),
+	BPF_ALU64_IMM(BPF_SUB, BPF_REG_2, 8),
+	/* add it to fp.  We now have either fp-4 or fp-8, but
+	 * we don't know which
+	 */
+	BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_10),
+	/* dereference it */
+	BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_2, 0),
+	BPF_EXIT_INSN(),
+	},
+	.errstr = "variable stack access var_off=(0xfffffffffffffff8; 0x4)",
+	.result = REJECT,
+	.prog_type = BPF_PROG_TYPE_LWT_IN,
+},
+{
+	"indirect variable-offset stack access",
+	.insns = {
+	/* Fill the top 8 bytes of the stack */
+	BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
+	/* Get an unknown value */
+	BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 0),
+	/* Make it small and 4-byte aligned */
+	BPF_ALU64_IMM(BPF_AND, BPF_REG_2, 4),
+	BPF_ALU64_IMM(BPF_SUB, BPF_REG_2, 8),
+	/* add it to fp.  We now have either fp-4 or fp-8, but
+	 * we don't know which
+	 */
+	BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_10),
+	/* dereference it indirectly */
+	BPF_LD_MAP_FD(BPF_REG_1, 0),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+	},
+	.fixup_map_hash_8b = { 5 },
+	.errstr = "variable stack read R2",
+	.result = REJECT,
+	.prog_type = BPF_PROG_TYPE_LWT_IN,
+},