From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793210412; b=dF8/Wz3/z5aFHM6XrOiBzhUJu2Tp7fzx0bv8CrA5/aG+g9mHThgys784gE/dDtn9+IV1 lMGFoQQQV12rSlnuWpQ6Cuy1nSBilIIbvXEaBKT3LnN9lYyK071iSE/gyoVn8lgL12h5q uGLSgzQfN4j2A2H1iVqqw4kK4mKKbZRTvOf5+Eg6KK3Re8UF5WvOHYUFNVLqRk3NTOLNJ +uM2szbo6VpN00mK1L/tvCY8le0p21+LlLvBcpjPRaL69hJkBrmmISOkVeKvdU11T1DMd uDh5Veq8sPS99V/JT+uJtPHZy6lz7GQPsYp5kBe3mpMVIcdjAZJkqgQjHb+4jm64OoQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793210412; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=d/reSfg/6rwExXzvB9+b/GJiAO3aH8l3SKstw81ePN4=; b=J40ACR2OVJNnkTvgCL1o8jZqbDRGe1YQSQplr7JkbDw0XOCVtmZmyUjdhk4VmUZwh9mJ s2g2HX0CC3wODfoMT2KPw8vq4Hz5wH7VSc7DX4UflD9SQiL0mVBG+fEXr8QDQEkBTa9i/ E3/wV2AuB9WVOQrVCTt3TVMjEy3Cg++jFJWTdphQBmUIhaJY4HP4ORVdh08l5UjxHg9j3 eh+I6igMFt+97jJtostwwL66aV4jaZ18JEFpXJkbiOsFBn/mwYiZuVaeTlWamueyDXwhq DveX83UlZp2eyneAvdQqU+G0+47Gqjorhd/UGZ/2p3MSBHSJD4J+lVoLgGg5diyn+wQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=nkB9B4su; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 55D35606A31A; Wed, 28 Oct 2026 18:00:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=nkB9B4su Received: by smtp.kernel.org (Postfix) with ESMTPSA id A07B41F01825; Wed, 28 Oct 2026 18:00:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793210412; bh=d/reSfg/6rwExXzvB9+b/GJiAO3aH8l3SKstw81ePN4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=nkB9B4sucP+k4VVBvYC72vTypJR4nLPVx+EwannLttlTEZj+Hg8OFY9pITRyRNZdw pfBoCe3BC7R5seXj0g2xTb3MryiIzBsJnKllRN8uSmVFoox+n26DXpRv8I1HRtITh4 CNuFznriF1MjKmyJKXGVidYlx+Au0FKwd8RpMtZU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Breno Leitao , Steven Rostedt , Sasha Levin Subject: [PATCH 5.15 018/571] ftrace: Take trace_array reference before accessing its ftrace_ops Date: Wed, 28 Oct 2026 17:52:45 +0100 Message-ID: <20261028170008.454586666@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028170008.009143722@linuxfoundation.org> References: <20261028170008.009143722@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Steven Rostedt [ Upstream commit 9100191e5acb2e5ea2313f436667bb5fce129f47 ] The trace instance files set_ftrace_filter and set_ftrace_notrace was updated to work with specific trace instances (trace_arrays). The issue is that when these files are opened, there is a small race window where it will use the ftrace_ops from the inode->private pointer to get a reference to the trace_array and then take its reference. The problem is that the ftrace_ops itself could be freed. If the rmdir on the instance happens at the same time the set_ftrace_filter file is opened, the rmdir could have also freed the ftrace_ops and referencing it will cause a use-after-free bug and crash the kernel. Instead, pass in the trace_array as the file private data (NULL for the top level instance), and then pass both the trace_array and the ftrace_ops to the ftrace_regex_open() function. If the trace_array is NULL, then it just uses the ftrace_ops without the need to take its reference (like normal). If the ftrace_ops is NULL, that is only the case for the top level instance and the global_ops can be used. This allows the trace_array to have its reference incremented before touching the ftrace_ops that could also be freed when the instance is. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260828223901.29e26edb@robin Fixes: 591dffdade9f0 ("ftrace: Allow for function tracing instance to filter functions") Reported-by: Breno Leitao Tested-by: Breno Leitao Closes: https://lore.kernel.org/all/apGORjltZgAiAYHT@gmail.com/ Signed-off-by: Steven Rostedt [ Replaced kzalloc_obj(*iter) with kzalloc(sizeof(*iter), GFP_KERNEL). ] Signed-off-by: Sasha Levin --- include/linux/ftrace.h | 5 +-- kernel/trace/ftrace.c | 59 ++++++++++++++++++++++------------ kernel/trace/trace.h | 4 +-- kernel/trace/trace_functions.c | 2 +- kernel/trace/trace_stack.c | 2 +- 5 files changed, 46 insertions(+), 26 deletions(-) diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index afc678d7fc869..c9a30ba3dc2d2 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -559,8 +559,9 @@ 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); @@ -774,7 +775,7 @@ 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(ops, buf, len, reset) ({ -ENODEV; }) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 0e5d6264735c0..644f5e060eb8a 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -3767,7 +3767,8 @@ ftrace_enabled_open(struct inode *inode, struct file *file) /** * ftrace_regex_open - initialize function tracer filter files - * @ops: The ftrace_ops that hold the hash filters + * @tr: The trace_array that holds the ftrace_ops [optional] + * @ops: The ftrace_ops that hold the hash filters [optional] * @flag: The type of filter to process * @inode: The inode, usually passed in to your open routine * @file: The file, usually passed in to your open routine @@ -3780,25 +3781,46 @@ ftrace_enabled_open(struct inode *inode, struct file *file) * ftrace_notrace_write() if @flag has FTRACE_ITER_NOTRACE set. * tracing_lseek() should be used as the lseek routine, and * release must call ftrace_regex_release(). + * + * Note, If @tr is not NULL, its reference has to be taken before + * @ops may be referenced. + * If @ops is NULL and @tr is not, then @tr->ops is used. + * If @tr is NULL and @ops is not then @ops->private is uesd for @tr. + * If both @tr and @ops are NULL, then the &global_ops is + * to be used, and @tr will be the global_ops.private pointer. + * + * 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 (!tr) { + if (!ops) + ops = &global_ops; + tr = ops->private; + } + if (tracing_check_open_get_tr(tr)) return -ENODEV; + if (!ops) + ops = tr->ops; + + if (WARN_ON_ONCE(!ops)) + goto out; + + ftrace_ops_init(ops); + + ret = -ENOMEM; iter = kzalloc(sizeof(*iter), GFP_KERNEL); if (!iter) goto out; @@ -3876,21 +3898,19 @@ 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); } @@ -6169,15 +6189,15 @@ 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); } /* @@ -6202,14 +6222,13 @@ 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); trace_create_file("enabled_functions", TRACE_MODE_READ, d_tracer, NULL, &ftrace_enabled_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 a632965446b8e..4e99f9b5c2125 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -1093,7 +1093,7 @@ 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); @@ -1116,11 +1116,11 @@ static inline void clear_ftrace_function_probes(struct trace_array *tr) { } +#define ftrace_create_filter_files(tr, parent) do { } while (0) /* * 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 18b8580971f6b..37a9b31e776ad 100644 --- a/kernel/trace/trace_functions.c +++ b/kernel/trace/trace_functions.c @@ -90,7 +90,7 @@ int ftrace_create_function_files(struct trace_array *tr, if (!tr->ops) return -EINVAL; - 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 5a48dba912eae..c6b2f622ffa12 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