From ae0faa924d07392a3c6b085df509080a3ada0e1a Mon Sep 17 00:00:00 2001 From: David Lechner Date: Tue, 31 Oct 2023 16:05:19 -0500 Subject: [PATCH] iio: triggered-buffer: prevent possible freeing of wrong buffer commit bce61476dc82f114e24e9c2e11fb064781ec563c upstream. Commit ee708e6baacd ("iio: buffer: introduce support for attaching more IIO buffers") introduced support for multiple buffers per indio_dev but left indio_dev->buffer for a few legacy use cases. In the case of the triggered buffer, iio_triggered_buffer_cleanup() still assumes that indio_dev->buffer points to the buffer allocated by iio_triggered_buffer_setup_ext(). However, since iio_triggered_buffer_setup_ext() now calls iio_device_attach_buffer() to attach the buffer, indio_dev->buffer will only point to the buffer allocated by iio_device_attach_buffer() if it the first buffer attached. This adds a check to make sure that no other buffer has been attached yet to ensure that indio_dev->buffer will be assigned when iio_device_attach_buffer() is called. As per discussion in the review thread, we may want to deal with multiple triggers per device, but this is a fix for the issue in the meantime and any such support would be unlikely to be suitable for a backport. Fixes: ee708e6baacd ("iio: buffer: introduce support for attaching more IIO buffers") Signed-off-by: David Lechner Acked-by: Nuno Sa Link: https://lore.kernel.org/r/20231031210521.1661552-1-dlechner@baylibre.com Cc: Signed-off-by: Jonathan Cameron Signed-off-by: Greg Kroah-Hartman --- drivers/iio/buffer/industrialio-triggered-buffer.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/iio/buffer/industrialio-triggered-buffer.c b/drivers/iio/buffer/industrialio-triggered-buffer.c index c7671b1..c065159 100644 --- a/drivers/iio/buffer/industrialio-triggered-buffer.c +++ b/drivers/iio/buffer/industrialio-triggered-buffer.c @@ -46,6 +46,16 @@ int iio_triggered_buffer_setup_ext(struct iio_dev *indio_dev, struct iio_buffer *buffer; int ret; + /* + * iio_triggered_buffer_cleanup() assumes that the buffer allocated here + * is assigned to indio_dev->buffer but this is only the case if this + * function is the first caller to iio_device_attach_buffer(). If + * indio_dev->buffer is already set then we can't proceed otherwise the + * cleanup function will try to free a buffer that was not allocated here. + */ + if (indio_dev->buffer) + return -EADDRINUSE; + buffer = iio_kfifo_allocate(); if (!buffer) { ret = -ENOMEM; -- 2.7.4