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authorAshutosh Naik <ashutosh.naik@gmail.com>2006-01-08 01:04:25 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-01-08 20:14:03 -0800
commiteea8b54dc0dceb740da697a89c54d20dde340306 (patch)
treec5f42385a174aa38aeb251eec361557a2b31d047
parentb368fae6abaa1736b8f26128c32947d47237b8e5 (diff)
[PATCH] modules: prevent overriding of symbols
Ensure that an exported symbol does not already exist in the kernel or in some other module's exported symbol table. This is done by checking the symbol tables for the exported symbol at the time of loading the module. Currently this is done after the relocation of the symbol. Signed-off-by: Ashutosh Naik <ashutosh.naik@gmail.com> Signed-off-by: Anand Krishnan <anandhkrishnan@yahoo.co.in> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--kernel/module.c39
1 files changed, 39 insertions, 0 deletions
diff --git a/kernel/module.c b/kernel/module.c
index 5d9078d6f0fa..fb6f091f5940 100644
--- 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;