kbuild: do not segfault in modpost if MODVERDIR is not defined

A combination of calling modpost with option -a and MODVERDIR undefined
caused segmentation fault. So provide a default value and accept the
error messages it generates instead.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

diff --git a/scripts/mod/sumversion.c b/scripts/mod/sumversion.c
index 5c07545..8a28756 100644 (file)
--- a/scripts/mod/sumversion.c
+++ b/scripts/mod/sumversion.c
@@ -381,8 +381,11 @@ void get_src_version(const char *modname, char sum[], unsigned sumlen)
        struct md4_ctx md;
        char *sources, *end, *fname;
        const char *basename;
-       char filelist[strlen(getenv("MODVERDIR")) + strlen("/") +
-                     strlen(modname) - strlen(".o") + strlen(".mod") + 1 ];
+       char filelist[PATH_MAX + 1];
+       char *modverdir = getenv("MODVERDIR");
+
+       if (!modverdir)
+               modverdir = ".";
 
        /* Source files for module are in .tmp_versions/modname.mod,
           after the first line. */
@@ -390,7 +393,7 @@ void get_src_version(const char *modname, char sum[], unsigned sumlen)
                basename = strrchr(modname, '/') + 1;
        else
                basename = modname;
-       sprintf(filelist, "%s/%.*s.mod", getenv("MODVERDIR"),
+       sprintf(filelist, "%s/%.*s.mod", modverdir,
                (int) strlen(basename) - 2, basename);
 
        file = grab_file(filelist, &len);