From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 989C0425CF5; Sat, 12 Sep 2026 11:41:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789213300; cv=none; b=tyMLIi/wOnJ17KUJnxw7xRNy8j90gHkrSSMOEoi7bP0zgQ0JCO1uqbz2OXJHwMw5Ro5YdURTg+EMvvYy4cpeS7p3fpx6e1lEishSlWfpW4xT8WkdlOljgpc+ZWM6j08EcmxngmLVr2E9l1a3yZl19g2iDbgVAR9MYhWXJL29nCI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789213300; c=relaxed/simple; bh=z28ezUXRpNugMxOnYYLWKubOt+SHBjbx6r3g4r4CKGI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=esIPxfrTQSoMzA+oQs4joIL+OfoOAYB+Lj4SW/CeFqATL6lpN8PANdPbZ4QlAzdUsrAcOByjgfTsj5e1i0WA5Kn6Dlqs5a8RKXG6+EbkgFcbCYq8h7n/6g3llPDgefbeV4qjnb5/kxi9KhugVkxtdtgjFO5wSJwZgvuaTPm2D6A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=HOjNaXZf; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="HOjNaXZf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3968F1F000FF; Sat, 12 Sep 2026 11:41:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789213299; bh=F2ZiJoz6eEED+xLbLCFlZi8zHgtzSS53PNQucOQp4Zk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=HOjNaXZfPcOCJvnAljlD2m6Vf1qaHSmSKkU3/lVnDvxzwDEmi1ajx7YJPpMS9DaOy LidC1XL1vUrBF3QAv2DyoFbDVb5E8fiJtQzVKr1ixDCrH9yNiwaB462wWkCPpTW7ZP COuw8T9oXWKZ5vLUWKrk//dDCayCfkOVXXMKeRt4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, sashiko-bot@kernel.org, Steven Rostedt Subject: [PATCH 6.12 0051/1376] ftrace: Synchronize the initialization of ftrace_ops Date: Sat, 12 Sep 2026 08:41:17 +0200 Message-ID: <20260912065608.696978014@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065607.535295758@linuxfoundation.org> References: <20260912065607.535295758@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Steven Rostedt commit 4617721c502b2ddaa4e324e86da4997edf738fa5 upstream. There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman --- kernel/trace/ftrace.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -76,6 +76,8 @@ .func_hash = &opsname.local_hash, \ .local_hash.regex_lock = __MUTEX_INITIALIZER(opsname.local_hash.regex_lock), \ .subop_list = LIST_HEAD_INIT(opsname.subop_list), +/* Used only to synchronize the initialization of ftrace_ops */ +static DEFINE_MUTEX(ops_mutex); #else #define INIT_OPS_HASH(opsname) #endif @@ -160,11 +162,18 @@ const struct ftrace_ops ftrace_nop_ops = static inline void ftrace_ops_init(struct ftrace_ops *ops) { #ifdef CONFIG_DYNAMIC_FTRACE - if (!(ops->flags & FTRACE_OPS_FL_INITIALIZED)) { + unsigned long flags = smp_load_acquire(&ops->flags); + + if (!(flags & FTRACE_OPS_FL_INITIALIZED)) { + guard(mutex)(&ops_mutex); + /* Could have been initialized before lock taken */ + if (unlikely(ops->flags & FTRACE_OPS_FL_INITIALIZED)) + return; mutex_init(&ops->local_hash.regex_lock); INIT_LIST_HEAD(&ops->subop_list); ops->func_hash = &ops->local_hash; - ops->flags |= FTRACE_OPS_FL_INITIALIZED; + flags = ops->flags | FTRACE_OPS_FL_INITIALIZED; + smp_store_release(&ops->flags, flags); } #endif }