From: Steven Rostedt <rostedt@kernel.org>
To: linux-kernel@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Andrew Morton <akpm@linux-foundation.org>,
stable@vger.kernel.org, Jiri Olsa <jolsa@kernel.org>,
Leon Hwang <leon.hwang@linux.dev>
Subject: [for-linus][PATCH 04/12] ftrace: Protect direct_functions in update_ftrace_direct_del
Date: Sat, 08 Aug 2026 22:31:48 -0400 [thread overview]
Message-ID: <20260809023221.854869492@kernel.org> (raw)
In-Reply-To: 20260809023144.852271250@kernel.org
From: Leon Hwang <leon.hwang@linux.dev>
Fix accessing the __rcu pointer direct_functions with RCU protection.
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260730150411.88667-3-leon.hwang@linux.dev
Fixes: 8d2c1233f371 ("ftrace: Add update_ftrace_direct_del function")
Acked-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/ftrace.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index c5d1d0d42ccc..9ea39110927f 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -6512,6 +6512,7 @@ int update_ftrace_direct_del(struct ftrace_ops *ops, struct ftrace_hash *hash)
struct ftrace_hash *new_direct_functions;
struct ftrace_hash *new_filter_hash = NULL;
struct ftrace_hash *old_filter_hash;
+ struct ftrace_hash *direct_hash;
struct ftrace_func_entry *entry;
struct ftrace_func_entry *del;
unsigned long size;
@@ -6523,11 +6524,13 @@ int update_ftrace_direct_del(struct ftrace_ops *ops, struct ftrace_hash *hash)
return -EINVAL;
if (!(ops->flags & FTRACE_OPS_FL_ENABLED))
return -EINVAL;
- if (direct_functions == EMPTY_HASH)
- return -EINVAL;
mutex_lock(&direct_mutex);
+ direct_hash = rcu_dereference_protected(direct_functions, lockdep_is_held(&direct_mutex));
+ if (direct_hash == EMPTY_HASH)
+ goto out_unlock;
+
old_filter_hash = ops->func_hash ? ops->func_hash->filter_hash : NULL;
if (!hash_count(old_filter_hash))
@@ -6537,7 +6540,7 @@ int update_ftrace_direct_del(struct ftrace_ops *ops, struct ftrace_hash *hash)
size = 1 << hash->size_bits;
for (int i = 0; i < size; i++) {
hlist_for_each_entry(entry, &hash->buckets[i], hlist) {
- del = __ftrace_lookup_ip(direct_functions, entry->ip);
+ del = __ftrace_lookup_ip(direct_hash, entry->ip);
if (!del || del->direct != entry->direct)
goto out_unlock;
}
@@ -6548,7 +6551,7 @@ int update_ftrace_direct_del(struct ftrace_ops *ops, struct ftrace_hash *hash)
if (!new_filter_hash)
goto out_unlock;
- new_direct_functions = hash_sub(direct_functions, hash);
+ new_direct_functions = hash_sub(direct_hash, hash);
if (!new_direct_functions)
goto out_unlock;
@@ -6575,7 +6578,7 @@ int update_ftrace_direct_del(struct ftrace_ops *ops, struct ftrace_hash *hash)
/* free the new_direct_functions */
old_direct_functions = new_direct_functions;
} else {
- old_direct_functions = direct_functions;
+ old_direct_functions = direct_hash;
rcu_assign_pointer(direct_functions, new_direct_functions);
}
--
2.53.0
next prev parent reply other threads:[~2026-08-09 2:32 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-09 2:31 [for-linus][PATCH 00/12] tracing: Fixes for 7.2 Steven Rostedt
2026-08-09 2:31 ` [for-linus][PATCH 01/12] eventfs: Fix use-after-free in eventfs_remove_rec() Steven Rostedt
2026-08-09 2:31 ` [for-linus][PATCH 02/12] eventfs: Use children field for rcu head and add memory barriers Steven Rostedt
2026-08-09 2:31 ` [for-linus][PATCH 03/12] ftrace: Protect direct_functions in ftrace_find_rec_direct Steven Rostedt
2026-08-09 2:31 ` Steven Rostedt [this message]
2026-08-09 2:31 ` [for-linus][PATCH 05/12] ftrace: Protect direct_functions in update_ftrace_direct_mod Steven Rostedt
2026-08-09 2:31 ` [for-linus][PATCH 06/12] ftrace: Drop extra comma in trace_buffered_event_enable Steven Rostedt
2026-08-09 2:31 ` [for-linus][PATCH 07/12] ring-buffer: Use current_context for safe per-CPU buffer swap Steven Rostedt
2026-08-09 2:31 ` [for-linus][PATCH 08/12] ftrace: Fix off-by-one fentry site disable in ftrace_free_mem() Steven Rostedt
2026-08-09 2:31 ` [for-linus][PATCH 09/12] ring-buffer: Prevent resizing of persistent ring buffer Steven Rostedt
2026-08-09 2:31 ` [for-linus][PATCH 10/12] ring-buffer: Prevent subbuf order change when resizing is disabled Steven Rostedt
2026-08-09 2:31 ` [for-linus][PATCH 11/12] ring-buffer: Initialise reader page order in rb_allocate_cpu_buffer() Steven Rostedt
2026-08-09 2:31 ` [for-linus][PATCH 12/12] ring-buffer: Fix crash passing ERR_PTR to kthread_stop() Steven Rostedt
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