module: weaken locking assertion for oops path. (fe0d34d2) · Commits · 戴 / test

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: ("module: Sanitize RCU usage and locking") Reported-by:

He Kuang <hekuang@huawei.com> Cc: stable@kernel.org Acked-by:

Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by:

Rusty Russell <rusty@rustcorp.com.au>

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);

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