selftests/bpf: Check that JMP32 pointer vs zero jumps are not predictedgrafted

Add jmp32_ptr_vs_zero_jne: the fall-through of the 32-bit compare, which
the verifier used to skip, contains an out of bounds map value access,
hence w/o the previous patch the program is accepted. See previous patch
for detailed description.

Reported-by: Nicholas Carlini <npc@anthropic.com>
Suggested-by: Nicholas Carlini <npc@anthropic.com>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20260904083325.2083493-6-eddyz87@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

1 files changed, 44 insertions, 0 deletions

diff --git a/tools/lib/vsprintf.c b/tools/lib/vsprintf.c
new file mode 100644
index 000000000..8780b4cda
--- /dev/null
+++ b/tools/lib/vsprintf.c
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <sys/types.h>
+#include <linux/kernel.h>
+#include <stdio.h>
+
+int vscnprintf(char *buf, size_t size, const char *fmt, va_list args)
+{
+       int i = vsnprintf(buf, size, fmt, args);
+       ssize_t ssize = size;
+
+       return (i >= ssize) ? (ssize - 1) : i;
+}
+
+int scnprintf(char * buf, size_t size, const char * fmt, ...)
+{
+       ssize_t ssize = size;
+       va_list args;
+       int i;
+
+       va_start(args, fmt);
+       i = vsnprintf(buf, size, fmt, args);
+       va_end(args);
+
+       return (i >= ssize) ? (ssize - 1) : i;
+}
+
+int scnprintf_pad(char * buf, size_t size, const char * fmt, ...)
+{
+	ssize_t ssize = size;
+	va_list args;
+	int i;
+
+	va_start(args, fmt);
+	i = vscnprintf(buf, size, fmt, args);
+	va_end(args);
+
+	if (i < (int) size) {
+		for (; i < (int) size; i++)
+			buf[i] = ' ';
+		buf[i] = 0x0;
+	}
+
+	return (i >= ssize) ? (ssize - 1) : i;
+}