[for-linus][PATCH 05/12] ftrace: Protect direct_functions in update_ftrace_direct_mod
Steven Rostedt <[email protected]>
| Newsgroups | org.kernel.vger.stable,org.kernel.vger.linux-kernel |
|---|---|
| Message-ID | <[email protected]> |
From: Leon Hwang <[email protected]> Fix accessing the __rcu pointer direct_functions with RCU protection. Cc: [email protected] Link: https://patch.msgid.link/[email protected] Fixes: e93672f770d7 ("ftrace: Add update_ftrace_direct_mod function") Acked-by: Jiri Olsa <[email protected]> Signed-off-by: Leon Hwang <[email protected]> Signed-off-by: Steven Rostedt <[email protected]> --- kernel/trace/ftrace.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 9ea39110927f..414e425c2d80 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -6617,6 +6617,7 @@ int update_ftrace_direct_mod(struct ftrace_ops *ops, struct ftrace_hash *hash, b .func = ftrace_stub, .flags = FTRACE_OPS_FL_STUB, }; + struct ftrace_hash *direct_hash; struct ftrace_hash *orig_hash; unsigned long size, i; int err = -EINVAL; @@ -6627,8 +6628,6 @@ int update_ftrace_direct_mod(struct ftrace_ops *ops, struct ftrace_hash *hash, b return -EINVAL; if (!(ops->flags & FTRACE_OPS_FL_ENABLED)) return -EINVAL; - if (direct_functions == EMPTY_HASH) - return -EINVAL; /* * We can be called from within ops_func callback with direct_mutex @@ -6636,6 +6635,12 @@ int update_ftrace_direct_mod(struct ftrace_ops *ops, struct ftrace_hash *hash, b */ if (do_direct_lock) mutex_lock(&direct_mutex); + else + lockdep_assert_held_once(&direct_mutex); + + direct_hash = rcu_dereference_protected(direct_functions, lockdep_is_held(&direct_mutex)); + if (direct_hash == EMPTY_HASH) + goto unlock; orig_hash = ops->func_hash ? ops->func_hash->filter_hash : NULL; if (!orig_hash) @@ -6667,7 +6672,7 @@ int update_ftrace_direct_mod(struct ftrace_ops *ops, struct ftrace_hash *hash, b size = 1 << hash->size_bits; for (i = 0; i < size; i++) { hlist_for_each_entry(entry, &hash->buckets[i], hlist) { - tmp = __ftrace_lookup_ip(direct_functions, entry->ip); + tmp = __ftrace_lookup_ip(direct_hash, entry->ip); if (!tmp) continue; tmp->direct = entry->direct; -- 2.53.0