execv_git_cmd: Fix stack buffer overflow.

Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/exec_cmd.c b/exec_cmd.c
index 44bb2f23de926db59832a69a3205a320dfe61c4d..12eb36494ca467169aff4db35335b3fdadd4cbee 100644 (file)
--- a/exec_cmd.c
+++ b/exec_cmd.c
@@ -32,12 +32,14 @@ const char *git_exec_path(void)
 int execv_git_cmd(const char **argv)
 {
        char git_command[PATH_MAX + 1];
-       int len,  i;
+       int i;
        const char *paths[] = { current_exec_path,
                                getenv("GIT_EXEC_PATH"),
                                builtin_exec_path };
 
        for (i = 0; i < ARRAY_SIZE(paths); ++i) {
+               size_t len;
+               int rc;
                const char *exec_dir = paths[i];
                const char *tmp;
 
@@ -46,8 +48,9 @@ int execv_git_cmd(const char **argv)
                if (*exec_dir != '/') {
                        if (!getcwd(git_command, sizeof(git_command))) {
                                fprintf(stderr, "git: cannot determine "
-                                       "current directory\n");
-                               exit(1);
+                                       "current directory: %s\n",
+                                       strerror(errno));
+                               break;
                        }
                        len = strlen(git_command);
 
@@ -57,17 +60,28 @@ int execv_git_cmd(const char **argv)
                                while (*exec_dir == '/')
                                        exec_dir++;
                        }
-                       snprintf(git_command + len, sizeof(git_command) - len,
-                                "/%s", exec_dir);
+
+                       rc = snprintf(git_command + len,
+                                     sizeof(git_command) - len, "/%s",
+                                     exec_dir);
+                       if (rc < 0 || rc >= sizeof(git_command) - len) {
+                               fprintf(stderr, "git: command name given "
+                                       "is too long.\n");
+                               break;
+                       }
                } else {
+                       if (strlen(exec_dir) + 1 > sizeof(git_command)) {
+                               fprintf(stderr, "git: command name given "
+                                       "is too long.\n");
+                               break;
+                       }
                        strcpy(git_command, exec_dir);
                }
 
                len = strlen(git_command);
-               len += snprintf(git_command + len, sizeof(git_command) - len,
-                               "/git-%s", argv[0]);
-
-               if (sizeof(git_command) <= len) {
+               rc = snprintf(git_command + len, sizeof(git_command) - len,
+                             "/git-%s", argv[0]);
+               if (rc < 0 || rc >= sizeof(git_command) - len) {
                        fprintf(stderr,
                                "git: command name given is too long.\n");
                        break;