From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Matthew Garrett <matthewgarrett@google.com>,
James Morris James Morris <jmorris@namei.org>,
LSM List <linux-security-module@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>,
Ben Hutchings <ben@decadent.org.uk>,
Al Viro <viro@zeniv.linux.org.uk>,
stable@vger.kernel.org
Subject: [PATCH 2/7 v2] ftrace: Get a reference counter for the trace_array on filter files
Date: Fri, 11 Oct 2019 20:57:49 -0400 [thread overview]
Message-ID: <20191012005920.780394471@goodmis.org> (raw)
In-Reply-To: 20191012005747.210722465@goodmis.org
From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
The ftrace set_ftrace_filter and set_ftrace_notrace files are specific for
an instance now. They need to take a reference to the instance otherwise
there could be a race between accessing the files and deleting the instance.
It wasn't until the :mod: caching where these file operations stated
referencing the trace_arry directly.
Cc: stable@vger.kernel.org
Fixes: 673feb9d76ab3 ("ftrace: Add :mod: caching infrastructure to trace_array")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
kernel/trace/ftrace.c | 27 ++++++++++++++++++---------
1 file changed, 18 insertions(+), 9 deletions(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 62a50bf399d6..32c2eb167de0 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3540,21 +3540,22 @@ ftrace_regex_open(struct ftrace_ops *ops, int flag,
struct ftrace_hash *hash;
struct list_head *mod_head;
struct trace_array *tr = ops->private;
- int ret = 0;
+ int ret = -ENOMEM;
ftrace_ops_init(ops);
if (unlikely(ftrace_disabled))
return -ENODEV;
+ if (tr && trace_array_get(tr) < 0)
+ return -ENODEV;
+
iter = kzalloc(sizeof(*iter), GFP_KERNEL);
if (!iter)
- return -ENOMEM;
+ goto out;
- if (trace_parser_get_init(&iter->parser, FTRACE_BUFF_MAX)) {
- kfree(iter);
- return -ENOMEM;
- }
+ if (trace_parser_get_init(&iter->parser, FTRACE_BUFF_MAX))
+ goto out;
iter->ops = ops;
iter->flags = flag;
@@ -3584,13 +3585,13 @@ ftrace_regex_open(struct ftrace_ops *ops, int flag,
if (!iter->hash) {
trace_parser_put(&iter->parser);
- kfree(iter);
- ret = -ENOMEM;
goto out_unlock;
}
} else
iter->hash = hash;
+ ret = 0;
+
if (file->f_mode & FMODE_READ) {
iter->pg = ftrace_pages_start;
@@ -3602,7 +3603,6 @@ ftrace_regex_open(struct ftrace_ops *ops, int flag,
/* Failed */
free_ftrace_hash(iter->hash);
trace_parser_put(&iter->parser);
- kfree(iter);
}
} else
file->private_data = iter;
@@ -3610,6 +3610,13 @@ ftrace_regex_open(struct ftrace_ops *ops, int flag,
out_unlock:
mutex_unlock(&ops->func_hash->regex_lock);
+ out:
+ if (ret) {
+ kfree(iter);
+ if (tr)
+ trace_array_put(tr);
+ }
+
return ret;
}
@@ -5037,6 +5044,8 @@ int ftrace_regex_release(struct inode *inode, struct file *file)
mutex_unlock(&iter->ops->func_hash->regex_lock);
free_ftrace_hash(iter->hash);
+ if (iter->tr)
+ trace_array_put(iter->tr);
kfree(iter);
return 0;
--
2.23.0
next prev parent reply other threads:[~2019-10-12 0:57 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-12 0:57 [PATCH 0/7 v2] tracing: Fix tracefs lockdown and various clean ups Steven Rostedt
2019-10-12 0:57 ` [PATCH 1/7 v2] tracefs: Revert ccbd54ff54e8 ("tracefs: Restrict tracefs when the kernel is locked down") Steven Rostedt
2019-10-12 22:56 ` Linus Torvalds
2019-10-13 0:35 ` Steven Rostedt
2019-10-13 0:39 ` Steven Rostedt
2019-10-12 0:57 ` Steven Rostedt [this message]
2019-10-12 0:57 ` [PATCH 3/7 v2] tracing: Get trace_array reference for available_tracers files Steven Rostedt
2019-10-12 0:57 ` [PATCH 4/7 v2] tracing: Have trace events system open call tracing_open_generic_tr() Steven Rostedt
2019-10-12 2:09 ` Steven Rostedt
2019-10-12 0:57 ` [PATCH 5/7 v2] tracing: Add tracing_check_open_get_tr() Steven Rostedt
2019-10-12 0:57 ` [PATCH 6/7 v2] tracing: Add some more locked_down checks Steven Rostedt
2019-10-12 0:57 ` [PATCH 7/7 v2] tracing: Do not create tracefs files if tracefs lockdown is in effect Steven Rostedt
2021-04-13 8:13 ` Ondrej Mosnacek
2021-05-07 12:00 ` Ondrej Mosnacek
2021-05-07 13:26 ` Steven Rostedt
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