From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) (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 DC84035B657 for ; Fri, 28 Aug 2026 19:54:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=216.40.44.15 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787946860; cv=none; b=F403cWmYthcIevnTVs3m/ND2o3XTj+03TLnTq9bXDq5QJs/8xsNQvw3Aq1pvw5saIbB/PbjQfcbdOdbQ65rJq0+hMBUMlSJn+KQv4BtZbllkI3Nu1es1BLD4IGRslZLSjkeOd2lSM8FkxcpVmL7BhTTbgOzfZTJ0dx2eO+YTwhk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787946860; c=relaxed/simple; bh=tpFcNd3+ARgr9deCsnxBsTiuRNqriI6MS5kW/9S2MBk=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=WlJVI6hSezbvOPE/ZDSDeuPWYSf19UTorS43cHpCZIuYkg92LhTqZtGymUUY0nS1g+PJHqPyAGa6iMi0cCLZjCviAHH1XcBX0PNVqqakrd0XMwGLn6xNq2RQrddY6elbvkHo+AG0O9x/O4IV3S1OgqNzJX0Fr/EkzY3OEb/X1hM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org; spf=pass smtp.mailfrom=goodmis.org; dkim=pass (1024-bit key) header.d=goodmis.org header.i=@goodmis.org header.b=gVce8Sw5; arc=none smtp.client-ip=216.40.44.15 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=goodmis.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=goodmis.org header.i=@goodmis.org header.b="gVce8Sw5" Received: from omf18.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 7817A1C20DF; Fri, 28 Aug 2026 19:54:16 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf18.hostedemail.com (Postfix) with ESMTPA id 9ABF02F; Fri, 28 Aug 2026 19:54:14 +0000 (UTC) Date: Fri, 28 Aug 2026 15:55:04 -0400 From: Steven Rostedt To: Breno Leitao Cc: mark.rutland@arm.com, mhiramat@kernel.org, linux-trace-kernel@vger.kernel.org Subject: Re: ftrace: UAF in ftrace_regex_open() on a removed tracing instance Message-ID: <20260828155504.529c97e4@gandalf.local.home> In-Reply-To: <20260828140411.14108739@gandalf.local.home> References: <20260828104201.21aa9d08@gandalf.local.home> <20260828140411.14108739@gandalf.local.home> X-Mailer: Claws Mail 3.20.0git84 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: 9efmfp97357t97czm8rmcg16a1u5ii51 X-Rspamd-Server: rspamout08 X-Rspamd-Queue-Id: 9ABF02F X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX191LqbQQBNhluJj5SuuE1+Hm40uP6FEdDs= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=goodmis.org; h=date:from:to:cc:subject:message-id:in-reply-to:references:mime-version:content-type:content-transfer-encoding; s=dkim1; bh=CV1ZCmldjUu3sB1IbDPmsTqt35XXT0B5c6jUqaL04us=; b=gVce8Sw5pd4kAAm5Qq79Bv83BiIFaWlY29xXWud4PawDeRbF8vu1Yfn5POhb0XxYud1bPgqQNHNRW2Ds9SVT7bo5cdXKjFgMUZbgTU3V4318ONCc6DGOFtwB23Aea3LUnV126poW6PcMX7pZ4Oi9aGCtyoyMtl7JTDEj659hA3E= X-HE-Tag: 1787946854-127370 X-HE-Meta: U2FsdGVkX1/VbzNPVzLQ83qzHGbX0RPh7JWyBnLtIrbAmBVJvh9Tvy6YzOfZVNFtvd0INT6pTGuSqL5i8RvXdQKIBHDERkCDHrH3G57uxI4STXzSFN/tSVTopjgQ8HzU/OtaE7ZwP5taRbK46HKHVsYDTfHM4EWi6gQ636luxYvYPgQetQhr7BfPc/AAISN2Nd/BvKvdimOFndGOO3K8wBmMTyaJThBQgu8UCBW4wngQy5vYsJhtBZfDzuWRIfetwBz8oWy9Y5S0dMMuqI+EPH0zTxeLOSPaZDdcJFzPen/FnhLwtS+w24twcuXuW+/kE7L4ScvPYf7G2M2VeytOEfyP4bEJJLs6VBUCaagCHXtrOJ8Be4ELoIQuRjmNkdgx On Fri, 28 Aug 2026 14:04:11 -0400 Steven Rostedt wrote: > I guess the issue is that the ops may be freed before you get access to the > trace array. Anyway more needs to be changed. I may remove the extra > reference. No need to do it twice. Also since trace_stack may have the > issue too. Something more like this: diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 02bc5027523a..bd76a16a63af 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -866,8 +866,9 @@ unsigned long ftrace_get_addr_new(struct dyn_ftrace *rec); unsigned long ftrace_get_addr_curr(struct dyn_ftrace *rec); extern ftrace_func_t ftrace_trace_function; +struct trace_array; -int ftrace_regex_open(struct ftrace_ops *ops, int flag, +int ftrace_regex_open(struct trace_array *tr, struct ftrace_ops *ops, int flag, struct inode *inode, struct file *file); ssize_t ftrace_filter_write(struct file *file, const char __user *ubuf, size_t cnt, loff_t *ppos); @@ -1077,7 +1078,7 @@ static inline unsigned long ftrace_location(unsigned long ip) * have them defined when ftrace is not enabled, but these * functions may still be called. Use a macro instead of inline. */ -#define ftrace_regex_open(ops, flag, inod, file) ({ -ENODEV; }) +#define ftrace_regex_open(tr, ops, flag, inode, file) ({ -ENODEV; }) #define ftrace_set_early_filter(ops, buf, enable) do { } while (0) #define ftrace_set_filter_ip(ops, ip, remove, reset) ({ -ENODEV; }) #define ftrace_set_filter_ips(ops, ips, cnt, remove, reset) ({ -ENODEV; }) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index f9d80c7bd9f1..fa7c7186c02f 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -4677,6 +4677,7 @@ ftrace_avail_addrs_open(struct inode *inode, struct file *file) /** * ftrace_regex_open - initialize function tracer filter files + * @tr: The trace_array that holds the ftrace_ops [optional] * @ops: The ftrace_ops that hold the hash filters * @flag: The type of filter to process * @inode: The inode, usually passed in to your open routine @@ -4694,23 +4695,29 @@ ftrace_avail_addrs_open(struct inode *inode, struct file *file) * Returns: 0 on success or a negative errno value on failure */ int -ftrace_regex_open(struct ftrace_ops *ops, int flag, +ftrace_regex_open(struct trace_array *tr, struct ftrace_ops *ops, int flag, struct inode *inode, struct file *file) { - struct ftrace_iterator *iter; + struct ftrace_iterator *iter = NULL; struct ftrace_hash *hash; struct list_head *mod_head; - struct trace_array *tr = ops->private; - int ret = -ENOMEM; - - ftrace_ops_init(ops); + int ret = -ENODEV; if (unlikely(ftrace_disabled)) return -ENODEV; - if (tracing_check_open_get_tr(tr)) + if (tr && tracing_check_open_get_tr(tr)) return -ENODEV; + if (!ops) + ops = tr ? tr->ops : &global_ops; + + if (WARN_ON_ONCE(!ops)) + goto out; + + ftrace_ops_init(ops); + + ret = -ENOMEM; iter = kzalloc_obj(*iter); if (!iter) goto out; @@ -4788,21 +4795,19 @@ ftrace_regex_open(struct ftrace_ops *ops, int flag, static int ftrace_filter_open(struct inode *inode, struct file *file) { - struct ftrace_ops *ops = inode->i_private; + struct trace_array *tr = inode->i_private; - /* Checks for tracefs lockdown */ - return ftrace_regex_open(ops, - FTRACE_ITER_FILTER | FTRACE_ITER_DO_PROBES, - inode, file); + return ftrace_regex_open(tr, NULL, + FTRACE_ITER_FILTER | FTRACE_ITER_DO_PROBES, + inode, file); } static int ftrace_notrace_open(struct inode *inode, struct file *file) { - struct ftrace_ops *ops = inode->i_private; + struct trace_array *tr = inode->i_private; - /* Checks for tracefs lockdown */ - return ftrace_regex_open(ops, FTRACE_ITER_NOTRACE, + return ftrace_regex_open(tr, NULL, FTRACE_ITER_NOTRACE, inode, file); } @@ -7492,15 +7497,15 @@ static const struct file_operations ftrace_graph_notrace_fops = { }; #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ -void ftrace_create_filter_files(struct ftrace_ops *ops, +void ftrace_create_filter_files(struct trace_array *tr, struct dentry *parent) { trace_create_file("set_ftrace_filter", TRACE_MODE_WRITE, parent, - ops, &ftrace_filter_fops); + tr, &ftrace_filter_fops); trace_create_file("set_ftrace_notrace", TRACE_MODE_WRITE, parent, - ops, &ftrace_notrace_fops); + tr, &ftrace_notrace_fops); } /* @@ -7525,7 +7530,6 @@ void ftrace_destroy_filter_files(struct ftrace_ops *ops) static __init int ftrace_init_dyn_tracefs(struct dentry *d_tracer) { - trace_create_file("available_filter_functions", TRACE_MODE_READ, d_tracer, NULL, &ftrace_avail_fops); @@ -7538,7 +7542,7 @@ static __init int ftrace_init_dyn_tracefs(struct dentry *d_tracer) trace_create_file("touched_functions", TRACE_MODE_READ, d_tracer, NULL, &ftrace_touched_fops); - ftrace_create_filter_files(&global_ops, d_tracer); + ftrace_create_filter_files(NULL, d_tracer); #ifdef CONFIG_FUNCTION_GRAPH_TRACER trace_create_file("set_graph_function", TRACE_MODE_WRITE, d_tracer, diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 74a7a50d1e78..3c111ca88e32 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -1340,7 +1340,7 @@ extern void clear_ftrace_function_probes(struct trace_array *tr); int register_ftrace_command(struct ftrace_func_command *cmd); int unregister_ftrace_command(struct ftrace_func_command *cmd); -void ftrace_create_filter_files(struct ftrace_ops *ops, +void ftrace_create_filter_files(struct trace_array *tr, struct dentry *parent); void ftrace_destroy_filter_files(struct ftrace_ops *ops); @@ -1363,11 +1363,12 @@ static inline void clear_ftrace_function_probes(struct trace_array *tr) { } +static inline void ftrace_create_filter_files(struct trace_array *tr, + struct dentry *parent) { } /* * The ops parameter passed in is usually undefined. * This must be a macro. */ -#define ftrace_create_filter_files(ops, parent) do { } while (0) #define ftrace_destroy_filter_files(ops) do { } while (0) #endif /* CONFIG_FUNCTION_TRACER && CONFIG_DYNAMIC_FTRACE */ diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c index cd37f2013758..c879d43a5fbb 100644 --- a/kernel/trace/trace_functions.c +++ b/kernel/trace/trace_functions.c @@ -101,7 +101,7 @@ int ftrace_create_function_files(struct trace_array *tr, return ret; } - ftrace_create_filter_files(tr->ops, parent); + ftrace_create_filter_files(tr, parent); return 0; } diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c index 0aa2514a6593..e7f4e523587d 100644 --- a/kernel/trace/trace_stack.c +++ b/kernel/trace/trace_stack.c @@ -499,7 +499,7 @@ stack_trace_filter_open(struct inode *inode, struct file *file) struct ftrace_ops *ops = inode->i_private; /* Checks for tracefs lockdown */ - return ftrace_regex_open(ops, FTRACE_ITER_FILTER, + return ftrace_regex_open(NULL, ops, FTRACE_ITER_FILTER, inode, file); } -- 2.53.0 -- Steve