selftests/bpf: add more test cases for check_cfg()

Add a few more simple cases to validate proper privileged vs unprivileged loop detection behavior. conditional_loop2 is the one reported by Hao Sun that triggered this set of fixes. Suggested-by: Hao Sun <[email protected]> Signed-off-by: Andrii Nakryiko <[email protected]>
danielocfb · Nov 9, 2023 · 64221bf · 64221bf
1 parent a590388
commit 64221bf
Showing 1 changed file with 62 additions and 0 deletions.
diff --git a/tools/testing/selftests/bpf/progs/verifier_cfg.c b/tools/testing/selftests/bpf/progs/verifier_cfg.c
@@ -97,4 +97,66 @@ l0_%=:	r2 = r0;					\
 "	::: __clobber_all);
 }
 
+SEC("socket")
+__description("conditional loop (2)")
+__success
+__failure_unpriv __msg_unpriv("back-edge from insn 10 to 11")
+__naked void conditional_loop2(void)
+{
+	asm volatile ("					\
+	r9 = 2 ll;					\
+	r3 = 0x20 ll;					\
+	r4 = 0x35 ll;					\
+	r8 = r4;					\
+	goto l1_%=;					\
+l0_%=:	r9 -= r3;					\
+	r9 -= r4;					\
+	r9 -= r8;					\
+l1_%=:	r8 += r4;					\
+	if r8 < 0x64 goto l0_%=;			\
+	r0 = r9;					\
+	exit;						\
+"	::: __clobber_all);
+}
+
+SEC("socket")
+__description("unconditional loop after conditional jump")
+__failure __msg("infinite loop detected")
+__failure_unpriv __msg_unpriv("back-edge from insn 3 to 2")
+__naked void uncond_loop_after_cond_jmp(void)
+{
+	asm volatile ("					\
+	r0 = 0;						\
+	if r0 > 0 goto l1_%=;				\
+l0_%=:	r0 = 1;						\
+	goto l0_%=;					\
+l1_%=:	exit;						\
+"	::: __clobber_all);
+}
+
+
+__naked __noinline __used
+static unsigned long never_ending_subprog()
+{
+	asm volatile ("					\
+	r0 = r1;					\
+	goto -1;					\
+"	::: __clobber_all);
+}
+
+SEC("socket")
+__description("unconditional loop after conditional jump")
+/* infinite loop is detected *after* check_cfg() */
+__failure __msg("infinite loop detected")
+__naked void uncond_loop_in_subprog_after_cond_jmp(void)
+{
+	asm volatile ("					\
+	r0 = 0;						\
+	if r0 > 0 goto l1_%=;				\
+l0_%=:	r0 += 1;					\
+	call never_ending_subprog;			\
+l1_%=:	exit;						\
+"	::: __clobber_all);
+}
+
 char _license[] SEC("license") = "GPL";