tracing: Have option files inc the trace array ref count

The option files update the options for a given trace array. For an
instance, if the file is opened and the instance is deleted, reading or
writing to the file will cause a use after free.

Up the ref count of the trace_array when an option file is opened.

Link: https://lkml.kernel.org/r/20230907024804.086679464@goodmis.org
Link: https://lore.kernel.org/all/1cb3aee2-19af-c472-e265-05176fe9bd84@huawei.com/
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Zheng Yejian <zhengyejian1@huawei.com>
Fixes: 8530dec63e7b4 ("tracing: Add tracing_check_open_get_tr()")
Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index b82df33..0608ad2 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -8988,12 +8988,33 @@ trace_options_write(struct file *filp, const char __user *ubuf, size_t cnt,
        return cnt;
 }
 
+static int tracing_open_options(struct inode *inode, struct file *filp)
+{
+       struct trace_option_dentry *topt = inode->i_private;
+       int ret;
+
+       ret = tracing_check_open_get_tr(topt->tr);
+       if (ret)
+               return ret;
+
+       filp->private_data = inode->i_private;
+       return 0;
+}
+
+static int tracing_release_options(struct inode *inode, struct file *file)
+{
+       struct trace_option_dentry *topt = file->private_data;
+
+       trace_array_put(topt->tr);
+       return 0;
+}
 
 static const struct file_operations trace_options_fops = {
-       .open = tracing_open_generic,
+       .open = tracing_open_options,
        .read = trace_options_read,
        .write = trace_options_write,
        .llseek = generic_file_llseek,
+       .release = tracing_release_options,
 };
 
 /*