selftests/bpf: Fix segfault in bpf_tcp_ca

Since commit ad9a7f96445b ("libbpf: Improve logging around BPF program
loading"), libbpf_debug_print() gets an additional prog_name parameter
but doesn't pass it to printf(). Since the format string now expects two
arguments, printf() may read uninitialized data and segfault. Pass
prog_name through.

Fixes: ad9a7f96445b ("libbpf: Improve logging around BPF program loading")
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211213183058.346066-1-jean-philippe@linaro.org

diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c b/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c
index 8daca0ac909fb25be38c8a76a7f5e6b81d04077a..8f7a1cef7d87acfca0e6af4209972dd83b53c110 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c
+++ b/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c
@@ -217,7 +217,7 @@ static bool found;
 static int libbpf_debug_print(enum libbpf_print_level level,
                              const char *format, va_list args)
 {
-       const char *log_buf;
+       const char *prog_name, *log_buf;
 
        if (level != LIBBPF_WARN ||
            !strstr(format, "-- BEGIN PROG LOAD LOG --")) {
@@ -225,15 +225,14 @@ static int libbpf_debug_print(enum libbpf_print_level level,
                return 0;
        }
 
-       /* skip prog_name */
-       va_arg(args, char *);
+       prog_name = va_arg(args, char *);
        log_buf = va_arg(args, char *);
        if (!log_buf)
                goto out;
        if (err_str && strstr(log_buf, err_str) != NULL)
                found = true;
 out:
-       printf(format, log_buf);
+       printf(format, prog_name, log_buf);
        return 0;
 }