From 07ffc4b90f0c2b4ec13ba804fdffc56d49dff93c Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Fri, 18 Aug 2023 16:58:46 +0100 Subject: audio/jackaudio: Avoid dynamic stack allocation in qjack_process() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Avoid a dynamic stack allocation in qjack_process(). Since this function is a JACK process callback, we are not permitted to malloc() here, so we allocate a working buffer in qjack_client_init() instead. The codebase has very few VLAs, and if we can get rid of them all we can make the compiler error on new additions. This is a defensive measure against security bugs where an on-stack dynamic allocation isn't correctly size-checked (e.g. CVE-2021-3527). Signed-off-by: Peter Maydell Reviewed-by: Marc-André Lureau Reviewed-by: Francisco Iglesias Reviewed-by: Christian Schoenebeck Message-id: 20230818155846.1651287-3-peter.maydell@linaro.org --- audio/jackaudio.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/audio/jackaudio.c b/audio/jackaudio.c index 7cb2a49..e1eaa34 100644 --- a/audio/jackaudio.c +++ b/audio/jackaudio.c @@ -70,6 +70,9 @@ typedef struct QJackClient { int buffersize; jack_port_t **port; QJackBuffer fifo; + + /* Used as workspace by qjack_process() */ + float **process_buffers; } QJackClient; @@ -267,22 +270,21 @@ static int qjack_process(jack_nframes_t nframes, void *arg) } /* get the buffers for the ports */ - float *buffers[c->nchannels]; for (int i = 0; i < c->nchannels; ++i) { - buffers[i] = jack_port_get_buffer(c->port[i], nframes); + c->process_buffers[i] = jack_port_get_buffer(c->port[i], nframes); } if (c->out) { if (likely(c->enabled)) { - qjack_buffer_read_l(&c->fifo, buffers, nframes); + qjack_buffer_read_l(&c->fifo, c->process_buffers, nframes); } else { for (int i = 0; i < c->nchannels; ++i) { - memset(buffers[i], 0, nframes * sizeof(float)); + memset(c->process_buffers[i], 0, nframes * sizeof(float)); } } } else { if (likely(c->enabled)) { - qjack_buffer_write_l(&c->fifo, buffers, nframes); + qjack_buffer_write_l(&c->fifo, c->process_buffers, nframes); } } @@ -448,6 +450,9 @@ static int qjack_client_init(QJackClient *c) jack_get_client_name(c->client)); } + /* Allocate working buffer for process callback */ + c->process_buffers = g_new(float *, c->nchannels); + jack_set_process_callback(c->client, qjack_process , c); jack_set_port_registration_callback(c->client, qjack_port_registration, c); jack_set_xrun_callback(c->client, qjack_xrun, c); @@ -579,6 +584,7 @@ static void qjack_client_fini_locked(QJackClient *c) qjack_buffer_free(&c->fifo); g_free(c->port); + g_free(c->process_buffers); c->state = QJACK_STATE_DISCONNECTED; /* fallthrough */ -- cgit v1.1