From: Eduard Zingerman <eddyz87@gmail.com>
Date: Mon, 8 Jan 2024 20:51:57 +0000 (+0200)
Subject: selftests/bpf: check if imprecise stack spills confuse infinite loop detection
X-Git-Tag: v6.9-rc1~159^2~423^2~37
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=c035b3e555b5642f786fb2d089a6ddf7b00eb374;p=thirdparty%2Fkernel%2Flinux.git

selftests/bpf: check if imprecise stack spills confuse infinite loop detection

Verify that infinite loop detection logic separates states with
identical register states but different imprecise scalars spilled to
stack.

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20240108205209.838365-4-maxtram95@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---

diff --git a/tools/testing/selftests/bpf/progs/verifier_loops1.c b/tools/testing/selftests/bpf/progs/verifier_loops1.c
index 71735dbf33d4f..e07b43b78fd21 100644
--- a/tools/testing/selftests/bpf/progs/verifier_loops1.c
+++ b/tools/testing/selftests/bpf/progs/verifier_loops1.c
@@ -259,4 +259,28 @@ l0_%=:	r2 += r1;					\
 "	::: __clobber_all);
 }
 
+SEC("xdp")
+__success
+__naked void not_an_inifinite_loop(void)
+{
+	asm volatile ("					\
+	call %[bpf_get_prandom_u32];			\
+	r0 &= 0xff;					\
+	*(u64 *)(r10 - 8) = r0;				\
+	r0 = 0;						\
+loop_%=:						\
+	r0 = *(u64 *)(r10 - 8);				\
+	if r0 > 10 goto exit_%=;			\
+	r0 += 1;					\
+	*(u64 *)(r10 - 8) = r0;				\
+	r0 = 0;						\
+	goto loop_%=;					\
+exit_%=:						\
+	r0 = 0;						\
+	exit;						\
+"	:
+	: __imm(bpf_get_prandom_u32)
+	: __clobber_all);
+}
+
 char _license[] SEC("license") = "GPL";