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ASoC: SOF: ipc4-mtrace: protect per-core nodes against multiple open

Message ID 20221018121332.20802-1-peter.ujfalusi@linux.intel.com
State New
Headers show
Series ASoC: SOF: ipc4-mtrace: protect per-core nodes against multiple open | expand

Commit Message

Peter Ujfalusi Oct. 18, 2022, 12:13 p.m. UTC
From: Kai Vehmanen <kai.vehmanen@linux.intel.com>

Add protection against multiple open of the mtrace/coreN debugfs
nodes. This is not supported in the implementation, and this will
show up as unexpected behaviour of the interface, and potential
use of already freed memory.

Fixes: f4ea22f7aa75 ("ASoC: SOF: ipc4: Add support for mtrace log extraction")
Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
---
 sound/soc/sof/ipc4-mtrace.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

Comments

Mark Brown Oct. 19, 2022, 12:32 p.m. UTC | #1
On Tue, 18 Oct 2022 15:13:32 +0300, Peter Ujfalusi wrote:
> From: Kai Vehmanen <kai.vehmanen@linux.intel.com>
> 
> Add protection against multiple open of the mtrace/coreN debugfs
> nodes. This is not supported in the implementation, and this will
> show up as unexpected behaviour of the interface, and potential
> use of already freed memory.
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-next

Thanks!

[1/1] ASoC: SOF: ipc4-mtrace: protect per-core nodes against multiple open
      commit: af6514f2f3828dc39c96cd4686ef5c9d8368626f

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark
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Patch

diff --git a/sound/soc/sof/ipc4-mtrace.c b/sound/soc/sof/ipc4-mtrace.c
index 9c7080041d08..70dea8ae706e 100644
--- a/sound/soc/sof/ipc4-mtrace.c
+++ b/sound/soc/sof/ipc4-mtrace.c
@@ -108,6 +108,7 @@  struct sof_mtrace_core_data {
 	int id;
 	u32 slot_offset;
 	void *log_buffer;
+	struct mutex buffer_lock; /* for log_buffer alloc/free */
 	u32 host_read_ptr;
 	u32 dsp_write_ptr;
 	/* pos update IPC arrived before the slot offset is known, queried */
@@ -128,14 +129,22 @@  static int sof_ipc4_mtrace_dfs_open(struct inode *inode, struct file *file)
 	struct sof_mtrace_core_data *core_data = inode->i_private;
 	int ret;
 
+	mutex_lock(&core_data->buffer_lock);
+
+	if (core_data->log_buffer) {
+		ret = -EBUSY;
+		goto out;
+	}
+
 	ret = debugfs_file_get(file->f_path.dentry);
 	if (unlikely(ret))
-		return ret;
+		goto out;
 
 	core_data->log_buffer = kmalloc(SOF_MTRACE_SLOT_SIZE, GFP_KERNEL);
 	if (!core_data->log_buffer) {
 		debugfs_file_put(file->f_path.dentry);
-		return -ENOMEM;
+		ret = -ENOMEM;
+		goto out;
 	}
 
 	ret = simple_open(inode, file);
@@ -144,6 +153,9 @@  static int sof_ipc4_mtrace_dfs_open(struct inode *inode, struct file *file)
 		debugfs_file_put(file->f_path.dentry);
 	}
 
+out:
+	mutex_unlock(&core_data->buffer_lock);
+
 	return ret;
 }
 
@@ -280,7 +292,10 @@  static int sof_ipc4_mtrace_dfs_release(struct inode *inode, struct file *file)
 
 	debugfs_file_put(file->f_path.dentry);
 
+	mutex_lock(&core_data->buffer_lock);
 	kfree(core_data->log_buffer);
+	core_data->log_buffer = NULL;
+	mutex_unlock(&core_data->buffer_lock);
 
 	return 0;
 }
@@ -563,6 +578,7 @@  static int ipc4_mtrace_init(struct snd_sof_dev *sdev)
 		struct sof_mtrace_core_data *core_data = &priv->cores[i];
 
 		init_waitqueue_head(&core_data->trace_sleep);
+		mutex_init(&core_data->buffer_lock);
 		core_data->sdev = sdev;
 		core_data->id = i;
 	}