modpost: simplify mod->name allocation

mod->name is set to the ELF filename with the suffix ".o" stripped.

The current code calls strdup() and free() to manipulate the string,
but a simpler approach is to pass new_module() with the name length
subtracted by 2.

Also, check if the passed filename ends with ".o" before stripping it.

The current code blindly chops the suffix:

    tmp[strlen(tmp) - 2] = '\0'

It will cause buffer under-run if strlen(tmp) < 2;

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 9269735..c1558ba 100644 (file)
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -172,11 +172,11 @@ static struct module *find_module(const char *modname)
        return NULL;
 }
 
-static struct module *new_module(const char *modname)
+static struct module *new_module(const char *name, size_t namelen)
 {
        struct module *mod;
 
-       mod = NOFAIL(malloc(sizeof(*mod) + strlen(modname) + 1));
+       mod = NOFAIL(malloc(sizeof(*mod) + namelen + 1));
        memset(mod, 0, sizeof(*mod));
 
        INIT_LIST_HEAD(&mod->exported_symbols);
@@ -184,8 +184,9 @@ static struct module *new_module(const char *modname)
        INIT_LIST_HEAD(&mod->missing_namespaces);
        INIT_LIST_HEAD(&mod->imported_namespaces);
 
-       strcpy(mod->name, modname);
-       mod->is_vmlinux = (strcmp(modname, "vmlinux") == 0);
+       memcpy(mod->name, name, namelen);
+       mod->name[namelen] = '\0';
+       mod->is_vmlinux = (strcmp(mod->name, "vmlinux") == 0);
 
        /*
         * Set mod->is_gpl_compatible to true by default. If MODULE_LICENSE()
@@ -2017,16 +2018,14 @@ static void read_symbols(const char *modname)
        if (!parse_elf(&info, modname))
                return;
 
-       {
-               char *tmp;
-
-               /* strip trailing .o */
-               tmp = NOFAIL(strdup(modname));
-               tmp[strlen(tmp) - 2] = '\0';
-               mod = new_module(tmp);
-               free(tmp);
+       if (!strends(modname, ".o")) {
+               error("%s: filename must be suffixed with .o\n", modname);
+               return;
        }
 
+       /* strip trailing .o */
+       mod = new_module(modname, strlen(modname) - strlen(".o"));
+
        if (!mod->is_vmlinux) {
                license = get_modinfo(&info, "license");
                if (!license)
@@ -2488,7 +2487,7 @@ static void read_dump(const char *fname)
 
                mod = find_module(modname);
                if (!mod) {
-                       mod = new_module(modname);
+                       mod = new_module(modname, strlen(modname));
                        mod->from_dump = true;
                }
                s = sym_add_exported(symname, mod, gpl_only);