[PATCH v2 01/18] tracing/remotes: Gate tracefs files opening on trace remote registration
From: Vincent Donnefort
Date: Fri Jun 05 2026 - 12:55:04 EST
Currently, if a remote fails to register, its resources will leak and
will not be properly tear-downed.
To prevent a user accessing a remote tracefs that is about to be
destroyed, keep track of the registered remotes in a global list,
similarly to trace instances. Gate the tracefs to open function based on
the presence of the remote in that list.
Signed-off-by: Vincent Donnefort <vdonnefort@xxxxxxxxxx>
diff --git a/kernel/trace/trace_remote.c b/kernel/trace/trace_remote.c
index d6c3f94d67cd..9f1669d433d5 100644
--- a/kernel/trace/trace_remote.c
+++ b/kernel/trace/trace_remote.c
@@ -39,6 +39,7 @@ struct trace_remote_iterator {
};
struct trace_remote {
+ struct list_head node;
struct trace_remote_callbacks *cbs;
void *priv;
struct trace_buffer *trace_buffer;
@@ -57,6 +58,9 @@ struct trace_remote {
bool tracing_on;
};
+static DEFINE_MUTEX(trace_remotes_lock);
+static LIST_HEAD(trace_remotes);
+
static bool trace_remote_loaded(struct trace_remote *remote)
{
return !!remote->trace_buffer;
@@ -170,6 +174,60 @@ static void trace_remote_reset(struct trace_remote *remote, int cpu)
trace_remote_try_unload(remote);
}
+static int trace_remote_tracefs_open(struct inode *inode, struct file *filp)
+{
+ void *i_private = inode->i_private;
+ struct trace_remote *r;
+
+ if (!i_private)
+ return -ENODEV;
+
+ guard(mutex)(&trace_remotes_lock);
+
+ /* i_private is either a struct trace_remote or a struct remote_event */
+ list_for_each_entry(r, &trace_remotes, node) {
+ if (r == i_private)
+ return 0;
+ if (!r->events)
+ continue;
+ if (i_private >= (void *)r->events &&
+ i_private < (void *)(r->events + r->nr_events))
+ return 0;
+ }
+
+ return -ENODEV;
+}
+
+#define DEFINE_TRACE_REMOTE_ATTRIBUTE_FUNCS(__name) \
+static int __name ## _open(struct inode *inode, struct file *file) \
+{ \
+ int ret = trace_remote_tracefs_open(inode, file); \
+ \
+ if (ret) \
+ return ret; \
+ \
+ return single_open(file, __name ## _show, inode->i_private); \
+}
+
+#define DEFINE_TRACE_REMOTE_ATTRIBUTE(__name) \
+DEFINE_TRACE_REMOTE_ATTRIBUTE_FUNCS(__name) \
+static const struct file_operations __name ## _fops = { \
+ .open = __name ## _open, \
+ .read = seq_read, \
+ .write = __name ## _write, \
+ .llseek = seq_lseek, \
+ .release = single_release, \
+}
+
+#define DEFINE_TRACE_REMOTE_SHOW_ATTRIBUTE(__name) \
+DEFINE_TRACE_REMOTE_ATTRIBUTE_FUNCS(__name) \
+static const struct file_operations __name ## _fops = { \
+ .open = __name ## _open, \
+ .read = seq_read, \
+ .llseek = seq_lseek, \
+ .release = single_release, \
+}
+
static ssize_t
tracing_on_write(struct file *filp, const char __user *ubuf, size_t cnt, loff_t *ppos)
{
@@ -198,7 +256,7 @@ static int tracing_on_show(struct seq_file *s, void *unused)
return 0;
}
-DEFINE_SHOW_STORE_ATTRIBUTE(tracing_on);
+DEFINE_TRACE_REMOTE_ATTRIBUTE(tracing_on);
static ssize_t buffer_size_kb_write(struct file *filp, const char __user *ubuf, size_t cnt,
loff_t *ppos)
@@ -235,7 +293,7 @@ static int buffer_size_kb_show(struct seq_file *s, void *unused)
return 0;
}
-DEFINE_SHOW_STORE_ATTRIBUTE(buffer_size_kb);
+DEFINE_TRACE_REMOTE_ATTRIBUTE(buffer_size_kb);
static int trace_remote_get(struct trace_remote *remote, int cpu)
{
@@ -593,6 +651,11 @@ static int trace_pipe_open(struct inode *inode, struct file *filp)
struct trace_remote *remote = inode->i_private;
struct trace_remote_iterator *iter;
int cpu = tracing_get_cpu(inode);
+ int ret;
+
+ ret = trace_remote_tracefs_open(inode, filp);
+ if (ret)
+ return ret;
guard(mutex)(&remote->lock);
@@ -602,7 +665,7 @@ static int trace_pipe_open(struct inode *inode, struct file *filp)
filp->private_data = iter;
- return IS_ERR(iter) ? PTR_ERR(iter) : 0;
+ return 0;
}
static int trace_pipe_release(struct inode *inode, struct file *filp)
@@ -734,22 +797,26 @@ static int trace_open(struct inode *inode, struct file *filp)
int cpu = tracing_get_cpu(inode);
int ret;
+ ret = trace_remote_tracefs_open(inode, filp);
+ if (ret)
+ return ret;
+
if (!(filp->f_mode & FMODE_READ))
return 0;
+ ret = seq_open(filp, &trace_sops);
+ if (ret)
+ return ret;
+
guard(mutex)(&remote->lock);
iter = trace_remote_iter(remote, cpu, TRI_NONCONSUMING);
- if (IS_ERR(iter))
+ if (IS_ERR(iter)) {
+ seq_release(inode, filp);
return PTR_ERR(iter);
-
- ret = seq_open(filp, &trace_sops);
- if (ret) {
- trace_remote_iter_free(iter);
- return ret;
}
- ((struct seq_file *)filp->private_data)->private = (void *)iter;
+ ((struct seq_file *)filp->private_data)->private = iter;
return 0;
}
@@ -932,8 +999,12 @@ int trace_remote_register(const char *name, struct trace_remote_callbacks *cbs,
}
ret = cbs->init ? cbs->init(remote->dentry, priv) : 0;
- if (ret)
+ if (ret) {
pr_err("Init failed for trace remote '%s' (%d)\n", name, ret);
+ } else {
+ guard(mutex)(&trace_remotes_lock);
+ list_add(&remote->node, &trace_remotes);
+ }
return ret;
}
@@ -1076,7 +1147,7 @@ static ssize_t remote_event_enable_write(struct file *filp, const char __user *u
return count;
}
-DEFINE_SHOW_STORE_ATTRIBUTE(remote_event_enable);
+DEFINE_TRACE_REMOTE_ATTRIBUTE(remote_event_enable);
static int remote_event_id_show(struct seq_file *s, void *unused)
{
@@ -1086,7 +1157,7 @@ static int remote_event_id_show(struct seq_file *s, void *unused)
return 0;
}
-DEFINE_SHOW_ATTRIBUTE(remote_event_id);
+DEFINE_TRACE_REMOTE_SHOW_ATTRIBUTE(remote_event_id);
static int remote_event_format_show(struct seq_file *s, void *unused)
{
@@ -1115,7 +1186,7 @@ static int remote_event_format_show(struct seq_file *s, void *unused)
return 0;
}
-DEFINE_SHOW_ATTRIBUTE(remote_event_format);
+DEFINE_TRACE_REMOTE_SHOW_ATTRIBUTE(remote_event_format);
static int remote_event_callback(const char *name, umode_t *mode, void **data,
const struct file_operations **fops)
@@ -1190,6 +1261,7 @@ static ssize_t remote_events_dir_enable_read(struct file *filp, char __user *ubu
}
static const struct file_operations remote_events_dir_enable_fops = {
+ .open = trace_remote_tracefs_open,
.write = remote_events_dir_enable_write,
.read = remote_events_dir_enable_read,
};
@@ -1214,6 +1286,7 @@ remote_events_dir_header_page_read(struct file *filp, char __user *ubuf, size_t
}
static const struct file_operations remote_events_dir_header_page_fops = {
+ .open = trace_remote_tracefs_open,
.read = remote_events_dir_header_page_read,
};
@@ -1237,6 +1310,7 @@ remote_events_dir_header_event_read(struct file *filp, char __user *ubuf, size_t
}
static const struct file_operations remote_events_dir_header_event_fops = {
+ .open = trace_remote_tracefs_open,
.read = remote_events_dir_header_event_read,
};
--
2.54.0.1032.g2f8565e1d1-goog