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module: make module_address_lookup safe

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module_address_lookup releases preemption then returns a pointer into
the module space.  The only user (kallsyms) copies the result, so just
do that under the preempt disable.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
2008-01-29 17:13:22 -05:00
parent bb9d3d56e7
commit 6dd06c9fbe
3 changed files with 30 additions and 25 deletions
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22
kernel/module.c
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@ -2230,14 +2230,13 @@ static const char *get_ksymbol(struct module *mod,
return mod->strtab + mod->symtab[best].st_name;
}
/* For kallsyms to ask for address resolution. NULL means not found.
We don't lock, as this is used for oops resolution and races are a
lesser concern. */
/* FIXME: Risky: returns a pointer into a module w/o lock */
const char *module_address_lookup(unsigned long addr,
unsigned long *size,
unsigned long *offset,
char **modname)
/* For kallsyms to ask for address resolution. NULL means not found. Careful
* not to lock to avoid deadlock on oopses, simply disable preemption. */
char *module_address_lookup(unsigned long addr,
unsigned long *size,
unsigned long *offset,
char **modname,
char *namebuf)
{
struct module *mod;
const char *ret = NULL;
@ -2252,8 +2251,13 @@ const char *module_address_lookup(unsigned long addr,
break;
}
}
/* Make a copy in here where it's safe */
if (ret) {
strncpy(namebuf, ret, KSYM_NAME_LEN - 1);
ret = namebuf;
}
preempt_enable();
return ret;
return (char *)ret;
}
int lookup_module_symbol_name(unsigned long addr, char *symname)