bpf: mark a NULL kfunc argument precisegrafted

check_kfunc_arg() allows bpf_register_is_null() for nullable arguments
w/o marking the underlying scalar register precise. Hence a checkpoint
created on such a path would prune against arbitrary scalar value.

Fixes: 3bda08b63670 ("bpf: Allow NULL buffers in bpf_dynptr_slice(_rw)")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260904-register-is-null-precise-fixes-v1-5-0f5a360ff15d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 44 insertions, 0 deletions

diff --git a/tools/perf/ui/keysyms.c b/tools/perf/ui/keysyms.c
new file mode 100644
index 000000000..b64564b07
--- /dev/null
+++ b/tools/perf/ui/keysyms.c
@@ -0,0 +1,44 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#include "keysyms.h"
+#include <linux/ctype.h>
+#include <linux/kernel.h>
+
+const char *key_name(int key, char *bf, size_t size)
+{
+	if (isprint(key)) {
+		scnprintf(bf, size, "%c", key); 
+	} else if (key < 32) {
+		scnprintf(bf, size, "Ctrl+%c", key + '@'); 
+	} else {
+		const char *name = NULL;
+
+		switch (key) {
+		case K_DOWN:	name = "Down";	    break;
+		case K_END:	name = "End";	    break;
+		case K_ENTER:	name = "Enter";	    break;
+		case K_ESC:	name = "ESC";	    break;
+		case K_F1:	name = "F1";	    break;
+		case K_HOME:	name = "Home";	    break;
+		case K_LEFT:	name = "Left";	    break;
+		case K_PGDN:	name = "PgDown";    break;
+		case K_PGUP:	name = "PgUp";	    break;
+		case K_RIGHT:	name = "Right";	    break;
+		case K_TAB:	name = "Tab";	    break;
+		case K_UNTAB:	name = "Untab";	    break;
+		case K_UP:	name = "Up";	    break;
+		case K_BKSPC:	name = "Backspace"; break;
+		case K_DEL:	name = "Del";	    break;
+		default:
+			if (key >= SL_KEY_F(1) && key <= SL_KEY_F(63))
+				scnprintf(bf, size, "F%d", key - SL_KEY_F(0));
+			else
+				scnprintf(bf, size, "Unknown (%d)", key);
+		}
+
+		if (name)
+			scnprintf(bf, size, "%s", name);
+	}
+
+	return bf;
+}