[PATCH] modules: prevent overriding of symbols

[linux-2.6-block.git] / kernel / module.c

diff --git a/kernel/module.c b/kernel/module.c
index 5d9078d6f0fa2b0a47a311b9b728e20291e9319c..fb6f091f594093c6f68c5684ca145866c38457b9 100644 (file)
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1204,6 +1204,39 @@ void *__symbol_get(const char *symbol)
 }
 EXPORT_SYMBOL_GPL(__symbol_get);
 
+/*
+ * Ensure that an exported symbol [global namespace] does not already exist
+ * in the Kernel or in some other modules exported symbol table.
+ */
+static int verify_export_symbols(struct module *mod)
+{
+       const char *name = NULL;
+       unsigned long i, ret = 0;
+       struct module *owner;
+       const unsigned long *crc;
+
+       for (i = 0; i < mod->num_syms; i++)
+               if (__find_symbol(mod->syms[i].name, &owner, &crc, 1)) {
+                       name = mod->syms[i].name;
+                       ret = -ENOEXEC;
+                       goto dup;
+               }
+
+       for (i = 0; i < mod->num_gpl_syms; i++)
+               if (__find_symbol(mod->gpl_syms[i].name, &owner, &crc, 1)) {
+                       name = mod->gpl_syms[i].name;
+                       ret = -ENOEXEC;
+                       goto dup;
+               }
+
+dup:
+       if (ret)
+               printk(KERN_ERR "%s: exports duplicate symbol %s (owned by %s)\n",
+                       mod->name, name, module_name(owner));
+
+       return ret;
+}
+
 /* Change all symbols so that sh_value encodes the pointer directly. */
 static int simplify_symbols(Elf_Shdr *sechdrs,
                            unsigned int symindex,
@@ -1772,6 +1805,12 @@ static struct module *load_module(void __user *umod,
                        goto cleanup;
        }
 
+        /* Find duplicate symbols */
+       err = verify_export_symbols(mod);
+
+       if (err < 0)
+               goto cleanup;
+
        /* Set up and sort exception table */
        mod->num_exentries = sechdrs[exindex].sh_size / sizeof(*mod->extable);
        mod->extable = extable = (void *)sechdrs[exindex].sh_addr;