Add tests validating that STACK_ZERO slots are preserved when slot is
partially overwritten with subregister spill.
Acked-by: Eduard Zingerman <eddyz87@xxxxxxxxx>
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
---
.../selftests/bpf/progs/verifier_spill_fill.c | 40 +++++++++++++++++++
1 file changed, 40 insertions(+)
diff --git a/tools/testing/selftests/bpf/progs/verifier_spill_fill.c b/tools/testing/selftests/bpf/progs/verifier_spill_fill.c
index 6115520154e3..d9dabae81176 100644
--- a/tools/testing/selftests/bpf/progs/verifier_spill_fill.c
+++ b/tools/testing/selftests/bpf/progs/verifier_spill_fill.c
@@ -4,6 +4,7 @@
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
#include "bpf_misc.h"
+#include <../../../tools/include/linux/filter.h>
struct {
__uint(type, BPF_MAP_TYPE_RINGBUF);
@@ -450,4 +451,43 @@ l0_%=: r1 >>= 16; \
: __clobber_all);
}
+SEC("raw_tp")
+__log_level(2)
+__success
+__msg("fp-8=0m??mmmm")
+__msg("fp-16=00mm??mm")
+__msg("fp-24=00mm???m")
+__naked void spill_subregs_preserve_stack_zero(void)
+{
+ asm volatile (
+ "call %[bpf_get_prandom_u32];"
+
+ /* 32-bit subreg spill with ZERO, MISC, and INVALID */
+ ".8byte %[fp1_u8_st_zero];" /* ZERO, LLVM-18+: *(u8 *)(r10 -1) = 0; */
+ "*(u8 *)(r10 -2) = r0;" /* MISC */
+ /* fp-3 and fp-4 stay INVALID */
+ "*(u32 *)(r10 -8) = r0;"
+
+ /* 16-bit subreg spill with ZERO, MISC, and INVALID */
+ ".8byte %[fp10_u16_st_zero];" /* ZERO, LLVM-18+: *(u16 *)(r10 -10) = 0; */
+ "*(u16 *)(r10 -12) = r0;" /* MISC */
+ /* fp-13 and fp-14 stay INVALID */
+ "*(u16 *)(r10 -16) = r0;"
+
+ /* 8-bit subreg spill with ZERO, MISC, and INVALID */
+ ".8byte %[fp18_u16_st_zero];" /* ZERO, LLVM-18+: *(u16 *)(r18 -10) = 0; */
+ "*(u16 *)(r10 -20) = r0;" /* MISC */
+ /* fp-21, fp-22, and fp-23 stay INVALID */
+ "*(u8 *)(r10 -24) = r0;"
+
+ "r0 = 0;"
+ "exit;"
+ :
+ : __imm(bpf_get_prandom_u32),
+ __imm_insn(fp1_u8_st_zero, BPF_ST_MEM(BPF_B, BPF_REG_FP, -1, 0)),
+ __imm_insn(fp10_u16_st_zero, BPF_ST_MEM(BPF_H, BPF_REG_FP, -10, 0)),
+ __imm_insn(fp18_u16_st_zero, BPF_ST_MEM(BPF_H, BPF_REG_FP, -18, 0))
+ : __clobber_all);
+}
+
char _license[] SEC("license") = "GPL";
--
2.34.1
