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>

1 files changed, 6 insertions, 3 deletions

diff --git a/scripts/mod/sumversion.c b/scripts/mod/sumversion.c
index 5c0754526a26..8a2875689e4d 100644
--- 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);