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| author | Rusty Russell <rusty@rustcorp.com.au> | 2015-07-29 05:52:14 +0930 |
|---|---|---|
| committer | Rusty Russell <rusty@rustcorp.com.au> | 2015-07-29 06:13:22 +0930 |
| commit | fe0d34d242fa1e0dec059e774d146a705420bc9a (patch) | |
| tree | a6e1fcef9810938b32af5079207143fe72bdbd5e /kernel | |
| parent | d61be4b3f2684b6d76ef8c1d28ecdeb9bb20fa8f (diff) | |
| download | linux-fe0d34d242fa1e0dec059e774d146a705420bc9a.tar.bz2 | |
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: 0be964be0d45 ("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>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/module.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/kernel/module.c b/kernel/module.c index 4d2b82e610e2..b86b7bf1be38 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -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); |