From 6dd06c9fbe025f542bce4cdb91790c0f91962722 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Tue, 29 Jan 2008 17:13:22 -0500 Subject: module: make module_address_lookup safe 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 --- kernel/module.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) (limited to 'kernel/module.c') diff --git a/kernel/module.c b/kernel/module.c index 12067ff34d01..e814cd7da634 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -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) -- cgit v1.2.2