diff --git a/tools/testing/selftests/bpf/progs/strobemeta.h b/tools/testing/selftests/bpf/progs/strobemeta.h
index 067eb625d01c..938765d87528 100644
--- a/tools/testing/selftests/bpf/progs/strobemeta.h
+++ b/tools/testing/selftests/bpf/progs/strobemeta.h
@@ -10,6 +10,14 @@
 #include <linux/types.h>
 #include "bpf_helpers.h"
 
+#define bpf_clamp_umax(VAR, UMAX)					\
+	asm volatile (							\
+		"if %0 <= %[max] goto +1\n"				\
+		"%0 = %[max]\n"						\
+		: "+r"(VAR)						\
+		: [max]"i"(UMAX)					\
+	)
+
 typedef uint32_t pid_t;
 struct task_struct {};
 
@@ -404,6 +412,7 @@ static __always_inline void *read_map_var(struct strobemeta_cfg *cfg,
 
 	len = bpf_probe_read_str(payload, STROBE_MAX_STR_LEN, map.tag);
 	if (len <= STROBE_MAX_STR_LEN) {
+		bpf_clamp_umax(len, STROBE_MAX_STR_LEN);
 		descr->tag_len = len;
 		payload += len;
 	}
@@ -421,6 +430,7 @@ static __always_inline void *read_map_var(struct strobemeta_cfg *cfg,
 		len = bpf_probe_read_str(payload, STROBE_MAX_STR_LEN,
 					 map.entries[i].key);
 		if (len <= STROBE_MAX_STR_LEN) {
+			bpf_clamp_umax(len, STROBE_MAX_STR_LEN);
 			descr->key_lens[i] = len;
 			payload += len;
 		}
@@ -428,6 +438,7 @@ static __always_inline void *read_map_var(struct strobemeta_cfg *cfg,
 		len = bpf_probe_read_str(payload, STROBE_MAX_STR_LEN,
 					 map.entries[i].val);
 		if (len <= STROBE_MAX_STR_LEN) {
+			bpf_clamp_umax(len, STROBE_MAX_STR_LEN);
 			descr->val_lens[i] = len;
 			payload += len;
 		}