[PATCH] selftests/bpf: add a 32-bit bounds deduction case

[Sun Jian <sun.jian.kdev@gmail.com>]

verifier_bounds.c already has 64-bit cross-sign-boundary bounds
deduction coverage.

Recent 32-bit signed/unsigned intersection tests extended the refinement
coverage, but a corresponding negative case is still missing.

Add a 32-bit selftest for that case and assert that the program is
rejected, confirming that verifier remains conservative there.

Signed-off-by: Sun Jian <sun.jian.kdev@gmail.com>
---
 .../selftests/bpf/progs/verifier_bounds.c     | 20 +++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/tools/testing/selftests/bpf/progs/verifier_bounds.c b/tools/testing/selftests/bpf/progs/verifier_bounds.c
index e526315c718a..242c3d6d23b1 100644
--- a/tools/testing/selftests/bpf/progs/verifier_bounds.c
+++ b/tools/testing/selftests/bpf/progs/verifier_bounds.c
@@ -2037,4 +2037,24 @@ __naked void signed_unsigned_intersection32_case2(void *ctx)
 	: __clobber_all);
 }
 
+SEC("socket")
+__description("32-bit bounds deduction cross sign boundary, two overlaps")
+__failure
+__flag(BPF_F_TEST_REG_INVARIANTS)
+__msg("frame pointer is read only")
+__naked void bounds_deduct_two_overlaps_32(void)
+{
+	asm volatile("				\
+	call %[bpf_get_prandom_u32];		\
+	r0 = (s8)r0;				\
+	w1 = 0xffffff80;			\
+	if w0 > w1 goto l0_%=;			\
+	if w0 < 128 goto l0_%=;			\
+	r10 = 0;				\
+l0_%=:	exit;					\
+"	:
+	: __imm(bpf_get_prandom_u32)
+	: __clobber_all);
+}
+
 char _license[] SEC("license") = "GPL";

base-commit: a989fde763f4f24209e4702f50a45be572340e68
-- 
2.43.0