From eea8b54dc0dceb740da697a89c54d20dde340306 Mon Sep 17 00:00:00 2001 From: Ashutosh Naik Date: Sun, 8 Jan 2006 01:04:25 -0800 Subject: [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 Signed-off-by: Anand Krishnan Cc: Rusty Russell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/module.c | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/kernel/module.c b/kernel/module.c index 5d9078d6f0f..fb6f091f594 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; -- cgit v1.2.3-70-g09d2