* [PATCH 2/7 v2] ftrace: Get a reference counter for the trace_array on filter files
[not found] <20191012005747.210722465@goodmis.org>
@ 2019-10-12 0:57 ` Steven Rostedt
2019-10-12 0:57 ` [PATCH 3/7 v2] tracing: Get trace_array reference for available_tracers files Steven Rostedt
1 sibling, 0 replies; 2+ messages in thread
From: Steven Rostedt @ 2019-10-12 0:57 UTC (permalink / raw)
To: linux-kernel
Cc: Linus Torvalds, Ingo Molnar, Andrew Morton, Matthew Garrett,
James Morris James Morris, LSM List, Linux API, Ben Hutchings,
Al Viro, stable
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
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [PATCH 3/7 v2] tracing: Get trace_array reference for available_tracers files
[not found] <20191012005747.210722465@goodmis.org>
2019-10-12 0:57 ` [PATCH 2/7 v2] ftrace: Get a reference counter for the trace_array on filter files Steven Rostedt
@ 2019-10-12 0:57 ` Steven Rostedt
1 sibling, 0 replies; 2+ messages in thread
From: Steven Rostedt @ 2019-10-12 0:57 UTC (permalink / raw)
To: linux-kernel
Cc: Linus Torvalds, Ingo Molnar, Andrew Morton, Matthew Garrett,
James Morris James Morris, LSM List, Linux API, Ben Hutchings,
Al Viro, stable
From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
As instances may have different tracers available, we need to look at the
trace_array descriptor that shows lists the available tracers for the
instance. But there's a race between opening the file and the admin from
deleting the instance. The trace_array_get() needs to be called before
accessing the trace_array.
Cc: stable@vger.kernel.org
Fixes: 607e2ea167e56 ("tracing: Set up infrastructure to allow tracers for instances")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
kernel/trace/trace.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 252f79c435f8..fa7d813b04c6 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4355,9 +4355,14 @@ static int show_traces_open(struct inode *inode, struct file *file)
if (tracing_disabled)
return -ENODEV;
+ if (trace_array_get(tr) < 0)
+ return -ENODEV;
+
ret = seq_open(file, &show_traces_seq_ops);
- if (ret)
+ if (ret) {
+ trace_array_put(tr);
return ret;
+ }
m = file->private_data;
m->private = tr;
@@ -4365,6 +4370,14 @@ static int show_traces_open(struct inode *inode, struct file *file)
return 0;
}
+static int show_traces_release(struct inode *inode, struct file *file)
+{
+ struct trace_array *tr = inode->i_private;
+
+ trace_array_put(tr);
+ return seq_release(inode, file);
+}
+
static ssize_t
tracing_write_stub(struct file *filp, const char __user *ubuf,
size_t count, loff_t *ppos)
@@ -4395,8 +4408,8 @@ static const struct file_operations tracing_fops = {
static const struct file_operations show_traces_fops = {
.open = show_traces_open,
.read = seq_read,
- .release = seq_release,
.llseek = seq_lseek,
+ .release = show_traces_release,
};
static ssize_t
--
2.23.0
^ permalink raw reply related [flat|nested] 2+ messages in thread