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[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>
This commit is contained in:
Ashutosh Naik 2006-01-08 01:04:25 -08:00 committed by Linus Torvalds
parent b368fae6ab
commit eea8b54dc0
1 changed files with 39 additions and 0 deletions
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39
kernel/module.c
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@ -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;