From 0f7c4063f8cd78b1a1e4858be39d3144cf7315dc Mon Sep 17 00:00:00 2001 From: =?utf8?q?David=20H=C3=A4rdeman?= Date: Mon, 1 May 2017 10:32:34 -0300 Subject: [PATCH] [media] ir-lirc-codec: let lirc_dev handle the lirc_buffer MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit ir_lirc_register() currently creates its own lirc_buffer before passing the lirc_driver to lirc_register_driver(). When a module is later unloaded, ir_lirc_unregister() gets called which performs a call to lirc_unregister_driver() and then free():s the lirc_buffer. The problem is that: a) there can still be a userspace app holding an open lirc fd when lirc_unregister_driver() returns; and b) the lirc_buffer contains "wait_queue_head_t wait_poll" which is potentially used as long as any userspace app is still around. The result is an oops which can be triggered quite easily by a userspace app monitoring its lirc fd using epoll() and not closing the fd promptly on device removal. The minimalistic fix is to let lirc_dev create the lirc_buffer since lirc_dev will then also free the buffer once it believes it is safe to do so. Signed-off-by: David Härdeman Signed-off-by: Sean Young Signed-off-by: Mauro Carvalho Chehab --- drivers/media/rc/ir-lirc-codec.c | 25 +++++++------------------ drivers/media/rc/lirc_dev.c | 13 ++++++++++++- 2 files changed, 19 insertions(+), 19 deletions(-) diff --git a/drivers/media/rc/ir-lirc-codec.c b/drivers/media/rc/ir-lirc-codec.c index de85f1d7ce43..8f0669c9894c 100644 --- a/drivers/media/rc/ir-lirc-codec.c +++ b/drivers/media/rc/ir-lirc-codec.c @@ -354,7 +354,6 @@ static const struct file_operations lirc_fops = { static int ir_lirc_register(struct rc_dev *dev) { struct lirc_driver *drv; - struct lirc_buffer *rbuf; int rc = -ENOMEM; unsigned long features = 0; @@ -362,19 +361,12 @@ static int ir_lirc_register(struct rc_dev *dev) if (!drv) return rc; - rbuf = kzalloc(sizeof(struct lirc_buffer), GFP_KERNEL); - if (!rbuf) - goto rbuf_alloc_failed; - - rc = lirc_buffer_init(rbuf, sizeof(int), LIRCBUF_SIZE); - if (rc) - goto rbuf_init_failed; - if (dev->driver_type != RC_DRIVER_IR_RAW_TX) { features |= LIRC_CAN_REC_MODE2; if (dev->rx_resolution) features |= LIRC_CAN_GET_REC_RESOLUTION; } + if (dev->tx_ir) { features |= LIRC_CAN_SEND_PULSE; if (dev->s_tx_mask) @@ -403,10 +395,12 @@ static int ir_lirc_register(struct rc_dev *dev) drv->minor = -1; drv->features = features; drv->data = &dev->raw->lirc; - drv->rbuf = rbuf; + drv->rbuf = NULL; drv->set_use_inc = &ir_lirc_open; drv->set_use_dec = &ir_lirc_close; drv->code_length = sizeof(struct ir_raw_event) * 8; + drv->chunk_size = sizeof(int); + drv->buffer_size = LIRCBUF_SIZE; drv->fops = &lirc_fops; drv->dev = &dev->dev; drv->rdev = dev; @@ -415,19 +409,15 @@ static int ir_lirc_register(struct rc_dev *dev) drv->minor = lirc_register_driver(drv); if (drv->minor < 0) { rc = -ENODEV; - goto lirc_register_failed; + goto out; } dev->raw->lirc.drv = drv; dev->raw->lirc.dev = dev; return 0; -lirc_register_failed: -rbuf_init_failed: - kfree(rbuf); -rbuf_alloc_failed: +out: kfree(drv); - return rc; } @@ -436,9 +426,8 @@ static int ir_lirc_unregister(struct rc_dev *dev) struct lirc_codec *lirc = &dev->raw->lirc; lirc_unregister_driver(lirc->drv->minor); - lirc_buffer_free(lirc->drv->rbuf); - kfree(lirc->drv->rbuf); kfree(lirc->drv); + lirc->drv = NULL; return 0; } diff --git a/drivers/media/rc/lirc_dev.c b/drivers/media/rc/lirc_dev.c index 8d60c9f00df9..42704552b005 100644 --- a/drivers/media/rc/lirc_dev.c +++ b/drivers/media/rc/lirc_dev.c @@ -52,6 +52,7 @@ struct irctl { struct mutex irctl_lock; struct lirc_buffer *buf; + bool buf_internal; unsigned int chunk_size; struct device dev; @@ -83,7 +84,7 @@ static void lirc_release(struct device *ld) put_device(ir->dev.parent); - if (ir->buf != ir->d.rbuf) { + if (ir->buf_internal) { lirc_buffer_free(ir->buf); kfree(ir->buf); } @@ -198,6 +199,7 @@ static int lirc_allocate_buffer(struct irctl *ir) if (d->rbuf) { ir->buf = d->rbuf; + ir->buf_internal = false; } else { ir->buf = kmalloc(sizeof(struct lirc_buffer), GFP_KERNEL); if (!ir->buf) { @@ -208,8 +210,11 @@ static int lirc_allocate_buffer(struct irctl *ir) err = lirc_buffer_init(ir->buf, chunk_size, buffer_size); if (err) { kfree(ir->buf); + ir->buf = NULL; goto out; } + + ir->buf_internal = true; } ir->chunk_size = ir->buf->chunk_size; @@ -362,6 +367,12 @@ int lirc_register_driver(struct lirc_driver *d) err = lirc_allocate_buffer(irctls[minor]); if (err) lirc_unregister_driver(minor); + else + /* + * This is kind of a hack but ir-lirc-codec needs + * access to the buffer that lirc_dev allocated. + */ + d->rbuf = irctls[minor]->buf; } return err ? err : minor; -- 2.20.1