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module: Use RCU in module_get_kallsym().

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The modules list and module::kallsyms can be accessed under RCU
assumption.

Iterate the modules with RCU protection, use rcu_dereference() to access
the kallsyms pointer.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250108090457.512198-6-bigeasy@linutronix.de
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
This commit is contained in:
Sebastian Andrzej Siewior 2025-01-08 10:04:34 +01:00 committed by Petr Pavlu
parent f013692392
commit c4fadf38de
1 changed files with 2 additions and 4 deletions
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6
kernel/module/kallsyms.c
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@ -381,13 +381,13 @@ int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
{
struct module *mod;
preempt_disable();
guard(rcu)();
list_for_each_entry_rcu(mod, &modules, list) {
struct mod_kallsyms *kallsyms;
if (mod->state == MODULE_STATE_UNFORMED)
continue;
kallsyms = rcu_dereference_sched(mod->kallsyms);
kallsyms = rcu_dereference(mod->kallsyms);
if (symnum < kallsyms->num_symtab) {
const Elf_Sym *sym = &kallsyms->symtab[symnum];
@ -396,12 +396,10 @@ int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
strscpy(name, kallsyms_symbol_name(kallsyms, symnum), KSYM_NAME_LEN);
strscpy(module_name, mod->name, MODULE_NAME_LEN);
*exported = is_exported(name, *value, mod);
preempt_enable();
return 0;
}
symnum -= kallsyms->num_symtab;
}
preempt_enable();
return -ERANGE;
}