selftests/bpf: Bump path and command buffer sizes in bpftool_helpers.c

The path length of 64 is way too low in some envirnoments, which leads
to subtle failures due to truncation [1].

Replace BPFTOOL_PATH_MAX_LEN with PATH_MAX, and set
BPFTOOL_FULL_CMD_MAX_LEN to double of PATH_MAX.

[1] https://github.com/libbpf/libbpf/actions/runs/22980753016/job/66719800527

Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20260312234820.439720-1-ihor.solodrai@linux.dev

diff --git a/tools/testing/selftests/bpf/bpftool_helpers.c b/tools/testing/selftests/bpf/bpftool_helpers.c
index 929fc257f4313d63f09221651ace1c21150dfe19..0a2a4f0a2794b9e8bf6c9b55840be40c2373a5d5 100644 (file)
--- a/tools/testing/selftests/bpf/bpftool_helpers.c
+++ b/tools/testing/selftests/bpf/bpftool_helpers.c
@@ -2,18 +2,18 @@
 #include <unistd.h>
 #include <string.h>
 #include <stdbool.h>
+#include <limits.h>
 
 #include "bpf_util.h"
 #include "bpftool_helpers.h"
 
-#define BPFTOOL_PATH_MAX_LEN           64
-#define BPFTOOL_FULL_CMD_MAX_LEN       512
+#define BPFTOOL_FULL_CMD_MAX_LEN       (PATH_MAX * 2)
 
 #define BPFTOOL_DEFAULT_PATH           "tools/sbin/bpftool"
 
 static int detect_bpftool_path(char *buffer, size_t size)
 {
-       char tmp[BPFTOOL_PATH_MAX_LEN];
+       char tmp[PATH_MAX];
        const char *env_path;
 
        /* First, check if BPFTOOL environment variable is set */
@@ -29,7 +29,7 @@ static int detect_bpftool_path(char *buffer, size_t size)
        /* Check default bpftool location (will work if we are running the
         * default flavor of test_progs)
         */
-       snprintf(tmp, BPFTOOL_PATH_MAX_LEN, "./%s", BPFTOOL_DEFAULT_PATH);
+       snprintf(tmp, sizeof(tmp), "./%s", BPFTOOL_DEFAULT_PATH);
        if (access(tmp, X_OK) == 0) {
                strscpy(buffer, tmp, size);
                return 0;
@@ -38,7 +38,7 @@ static int detect_bpftool_path(char *buffer, size_t size)
        /* Check alternate bpftool location (will work if we are running a
         * specific flavor of test_progs, e.g. cpuv4 or no_alu32)
         */
-       snprintf(tmp, BPFTOOL_PATH_MAX_LEN, "../%s", BPFTOOL_DEFAULT_PATH);
+       snprintf(tmp, sizeof(tmp), "../%s", BPFTOOL_DEFAULT_PATH);
        if (access(tmp, X_OK) == 0) {
                strscpy(buffer, tmp, size);
                return 0;
@@ -50,7 +50,7 @@ static int detect_bpftool_path(char *buffer, size_t size)
 
 static int run_command(char *args, char *output_buf, size_t output_max_len)
 {
-       static char bpftool_path[BPFTOOL_PATH_MAX_LEN] = {0};
+       static char bpftool_path[PATH_MAX] = {};
        bool suppress_output = !(output_buf && output_max_len);
        char command[BPFTOOL_FULL_CMD_MAX_LEN];
        FILE *f;
@@ -60,7 +60,7 @@ static int run_command(char *args, char *output_buf, size_t output_max_len)
        if (bpftool_path[0] == 0 && detect_bpftool_path(bpftool_path, sizeof(bpftool_path)))
                return 1;
 
-       ret = snprintf(command, BPFTOOL_FULL_CMD_MAX_LEN, "%s %s%s",
+       ret = snprintf(command, sizeof(command), "%s %s%s",
                       bpftool_path, args,
                       suppress_output ? " > /dev/null 2>&1" : "");
 
@@ -84,4 +84,3 @@ int get_bpftool_command_output(char *args, char *output_buf, size_t output_max_l
 {
        return run_command(args, output_buf, output_max_len);
 }
-