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Commit fe0d34d2 authored by Rusty Russell's avatar Rusty Russell
Browse files

module: weaken locking assertion for oops path. 



We don't actually hold the module_mutex when calling find_module_all
from module_kallsyms_lookup_name: that's because it's used by the oops
code and we don't want to deadlock.

However, access to the list read-only is safe if preempt is disabled,
so we can weaken the assertion.  Keep a strong version for external
callers though.

Fixes: 0be964be ("module: Sanitize RCU usage and locking")
Reported-by: default avatarHe Kuang <hekuang@huawei.com>
Cc: stable@kernel.org
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent d61be4b3

kernel/module.c

+6 −2
Original line number Diff line number Diff line
@@ -602,13 +602,16 @@ const struct kernel_symbol *find_symbol(const char *name, 
}

EXPORT_SYMBOL_GPL(find_symbol);



/* Search for module by name: must hold module_mutex. */

/*

 * Search for module by name: must hold module_mutex (or preempt disabled

 * for read-only access).

 */

static struct module *find_module_all(const char *name, size_t len,

				      bool even_unformed)

{

	struct module *mod;



	module_assert_mutex();

	module_assert_mutex_or_preempt();



	list_for_each_entry(mod, &modules, list) {

		if (!even_unformed && mod->state == MODULE_STATE_UNFORMED)
@@ -621,6 +624,7 @@ static struct module *find_module_all(const char *name, size_t len, 


struct module *find_module(const char *name)

{

	module_assert_mutex();

	return find_module_all(name, strlen(name), false);

}

EXPORT_SYMBOL_GPL(find_module);