7 files changed, 186 insertions, 106 deletions

diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index 73515d54e1cc..5c8429f23a89 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -130,6 +130,12 @@ struct ffs_epfile {
 
 	struct dentry			*dentry;
 
+	/*
+	 * Buffer for holding data from partial reads which may happen since
+	 * we’re rounding user read requests to a multiple of a max packet size.
+	 */
+	struct ffs_buffer		*read_buffer;	/* P: epfile->mutex */
+
 	char				name[5];
 
 	unsigned char			in;	/* P: ffs->eps_lock */
@@ -138,6 +144,12 @@ struct ffs_epfile {
 	unsigned char			_pad;
 };
 
+struct ffs_buffer {
+	size_t length;
+	char *data;
+	char storage[];
+};
+
 /*  ffs_io_data structure ***************************************************/
 
 struct ffs_io_data {
@@ -640,6 +652,49 @@ static void ffs_epfile_io_complete(struct usb_ep *_ep, struct usb_request *req)
 	}
 }
 
+static ssize_t ffs_copy_to_iter(void *data, int data_len, struct iov_iter *iter)
+{
+	ssize_t ret = copy_to_iter(data, data_len, iter);
+	if (likely(ret == data_len))
+		return ret;
+
+	if (unlikely(iov_iter_count(iter)))
+		return -EFAULT;
+
+	/*
+	 * Dear user space developer!
+	 *
+	 * TL;DR: To stop getting below error message in your kernel log, change
+	 * user space code using functionfs to align read buffers to a max
+	 * packet size.
+	 *
+	 * Some UDCs (e.g. dwc3) require request sizes to be a multiple of a max
+	 * packet size.  When unaligned buffer is passed to functionfs, it
+	 * internally uses a larger, aligned buffer so that such UDCs are happy.
+	 *
+	 * Unfortunately, this means that host may send more data than was
+	 * requested in read(2) system call.  f_fs doesn’t know what to do with
+	 * that excess data so it simply drops it.
+	 *
+	 * Was the buffer aligned in the first place, no such problem would
+	 * happen.
+	 *
+	 * Data may be dropped only in AIO reads.  Synchronous reads are handled
+	 * by splitting a request into multiple parts.  This splitting may still
+	 * be a problem though so it’s likely best to align the buffer
+	 * regardless of it being AIO or not..
+	 *
+	 * This only affects OUT endpoints, i.e. reading data with a read(2),
+	 * aio_read(2) etc. system calls.  Writing data to an IN endpoint is not
+	 * affected.
+	 */
+	pr_err("functionfs read size %d > requested size %zd, dropping excess data. "
+	       "Align read buffer size to max packet size to avoid the problem.\n",
+	       data_len, ret);
+
+	return ret;
+}
+
 static void ffs_user_copy_worker(struct work_struct *work)
 {
 	struct ffs_io_data *io_data = container_of(work, struct ffs_io_data,
@@ -650,9 +705,7 @@ static void ffs_user_copy_worker(struct work_struct *work)
 
 	if (io_data->read && ret > 0) {
 		use_mm(io_data->mm);
-		ret = copy_to_iter(io_data->buf, ret, &io_data->data);
-		if (ret != io_data->req->actual && iov_iter_count(&io_data->data))
-			ret = -EFAULT;
+		ret = ffs_copy_to_iter(io_data->buf, ret, &io_data->data);
 		unuse_mm(io_data->mm);
 	}
 
@@ -680,6 +733,58 @@ static void ffs_epfile_async_io_complete(struct usb_ep *_ep,
 	schedule_work(&io_data->work);
 }
 
+/* Assumes epfile->mutex is held. */
+static ssize_t __ffs_epfile_read_buffered(struct ffs_epfile *epfile,
+					  struct iov_iter *iter)
+{
+	struct ffs_buffer *buf = epfile->read_buffer;
+	ssize_t ret;
+	if (!buf)
+		return 0;
+
+	ret = copy_to_iter(buf->data, buf->length, iter);
+	if (buf->length == ret) {
+		kfree(buf);
+		epfile->read_buffer = NULL;
+	} else if (unlikely(iov_iter_count(iter))) {
+		ret = -EFAULT;
+	} else {
+		buf->length -= ret;
+		buf->data += ret;
+	}
+	return ret;
+}
+
+/* Assumes epfile->mutex is held. */
+static ssize_t __ffs_epfile_read_data(struct ffs_epfile *epfile,
+				      void *data, int data_len,
+				      struct iov_iter *iter)
+{
+	struct ffs_buffer *buf;
+
+	ssize_t ret = copy_to_iter(data, data_len, iter);
+	if (likely(data_len == ret))
+		return ret;
+
+	if (unlikely(iov_iter_count(iter)))
+		return -EFAULT;
+
+	/* See ffs_copy_to_iter for more context. */
+	pr_warn("functionfs read size %d > requested size %zd, splitting request into multiple reads.",
+		data_len, ret);
+
+	data_len -= ret;
+	buf = kmalloc(sizeof(*buf) + data_len, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+	buf->length = data_len;
+	buf->data = buf->storage;
+	memcpy(buf->storage, data + ret, data_len);
+	epfile->read_buffer = buf;
+
+	return ret;
+}
+
 static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
 {
 	struct ffs_epfile *epfile = file->private_data;
@@ -709,21 +814,40 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
 	if (halt && epfile->isoc)
 		return -EINVAL;
 
+	/* We will be using request and read_buffer */
+	ret = ffs_mutex_lock(&epfile->mutex, file->f_flags & O_NONBLOCK);
+	if (unlikely(ret))
+		goto error;
+
 	/* Allocate & copy */
 	if (!halt) {
+		struct usb_gadget *gadget;
+
+		/*
+		 * Do we have buffered data from previous partial read?  Check
+		 * that for synchronous case only because we do not have
+		 * facility to ‘wake up’ a pending asynchronous read and push
+		 * buffered data to it which we would need to make things behave
+		 * consistently.
+		 */
+		if (!io_data->aio && io_data->read) {
+			ret = __ffs_epfile_read_buffered(epfile, &io_data->data);
+			if (ret)
+				goto error_mutex;
+		}
+
 		/*
 		 * if we _do_ wait above, the epfile->ffs->gadget might be NULL
 		 * before the waiting completes, so do not assign to 'gadget'
 		 * earlier
 		 */
-		struct usb_gadget *gadget = epfile->ffs->gadget;
-		size_t copied;
+		gadget = epfile->ffs->gadget;
 
 		spin_lock_irq(&epfile->ffs->eps_lock);
 		/* In the meantime, endpoint got disabled or changed. */
 		if (epfile->ep != ep) {
-			spin_unlock_irq(&epfile->ffs->eps_lock);
-			return -ESHUTDOWN;
+			ret = -ESHUTDOWN;
+			goto error_lock;
 		}
 		data_len = iov_iter_count(&io_data->data);
 		/*
@@ -735,22 +859,17 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
 		spin_unlock_irq(&epfile->ffs->eps_lock);
 
 		data = kmalloc(data_len, GFP_KERNEL);
-		if (unlikely(!data))
-			return -ENOMEM;
-		if (!io_data->read) {
-			copied = copy_from_iter(data, data_len, &io_data->data);
-			if (copied != data_len) {
-				ret = -EFAULT;
-				goto error;
-			}
+		if (unlikely(!data)) {
+			ret = -ENOMEM;
+			goto error_mutex;
+		}
+		if (!io_data->read &&
+		    copy_from_iter(data, data_len, &io_data->data) != data_len) {
+			ret = -EFAULT;
+			goto error_mutex;
 		}
 	}
 
-	/* We will be using request */
-	ret = ffs_mutex_lock(&epfile->mutex, file->f_flags & O_NONBLOCK);
-	if (unlikely(ret))
-		goto error;
-
 	spin_lock_irq(&epfile->ffs->eps_lock);
 
 	if (epfile->ep != ep) {
@@ -803,18 +922,13 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
 			interrupted = ep->status < 0;
 		}
 
-		/*
-		 * XXX We may end up silently droping data here.  Since data_len
-		 * (i.e. req->length) may be bigger than len (after being
-		 * rounded up to maxpacketsize), we may end up with more data
-		 * then user space has space for.
-		 */
-		ret = interrupted ? -EINTR : ep->status;
-		if (io_data->read && ret > 0) {
-			ret = copy_to_iter(data, ret, &io_data->data);
-			if (!ret)
-				ret = -EFAULT;
-		}
+		if (interrupted)
+			ret = -EINTR;
+		else if (io_data->read && ep->status > 0)
+			ret = __ffs_epfile_read_data(epfile, data, ep->status,
+						     &io_data->data);
+		else
+			ret = ep->status;
 		goto error_mutex;
 	} else if (!(req = usb_ep_alloc_request(ep->ep, GFP_KERNEL))) {
 		ret = -ENOMEM;
@@ -980,6 +1094,8 @@ ffs_epfile_release(struct inode *inode, struct file *file)
 
 	ENTER();
 
+	kfree(epfile->read_buffer);
+	epfile->read_buffer = NULL;
 	ffs_data_closed(epfile->ffs);
 
 	return 0;
@@ -1605,19 +1721,24 @@ static void ffs_func_eps_disable(struct ffs_function *func)
 	unsigned count            = func->ffs->eps_count;
 	unsigned long flags;
 
-	spin_lock_irqsave(&func->ffs->eps_lock, flags);
 	do {
+		if (epfile)
+			mutex_lock(&epfile->mutex);
+		spin_lock_irqsave(&func->ffs->eps_lock, flags);
 		/* pending requests get nuked */
 		if (likely(ep->ep))
 			usb_ep_disable(ep->ep);
 		++ep;
+		spin_unlock_irqrestore(&func->ffs->eps_lock, flags);
 
 		if (epfile) {
 			epfile->ep = NULL;
+			kfree(epfile->read_buffer);
+			epfile->read_buffer = NULL;
+			mutex_unlock(&epfile->mutex);
 			++epfile;
 		}
 	} while (--count);
-	spin_unlock_irqrestore(&func->ffs->eps_lock, flags);
 }
 
 static int ffs_func_eps_enable(struct ffs_function *func)
@@ -2051,7 +2172,7 @@ static int __ffs_data_do_os_desc(enum ffs_os_desc_type type,
 
 		if (len < sizeof(*d) ||
 		    d->bFirstInterfaceNumber >= ffs->interfaces_count ||
-		    d->Reserved1)
+		    !d->Reserved1)
 			return -EINVAL;
 		for (i = 0; i < ARRAY_SIZE(d->Reserved2); ++i)
 			if (d->Reserved2[i])
@@ -2227,8 +2348,8 @@ static int __ffs_data_got_strings(struct ffs_data *ffs,
 {
 	u32 str_count, needed_count, lang_count;
 	struct usb_gadget_strings **stringtabs, *t;
-	struct usb_string *strings, *s;
 	const char *data = _data;
+	struct usb_string *s;
 
 	ENTER();
 
@@ -2286,7 +2407,6 @@ static int __ffs_data_got_strings(struct ffs_data *ffs,
 		stringtabs = vla_ptr(vlabuf, d, stringtabs);
 		t = vla_ptr(vlabuf, d, stringtab);
 		s = vla_ptr(vlabuf, d, strings);
-		strings = s;
 	}
 
 	/* For each language */
@@ -2729,6 +2849,7 @@ static int _ffs_func_bind(struct usb_configuration *c,
 		func->ffs->ss_descs_count;
 
 	int fs_len, hs_len, ss_len, ret, i;
+	struct ffs_ep *eps_ptr;
 
 	/* Make it a single chunk, less management later on */
 	vla_group(d);
@@ -2777,12 +2898,9 @@ static int _ffs_func_bind(struct usb_configuration *c,
 	       ffs->raw_descs_length);
 
 	memset(vla_ptr(vlabuf, d, inums), 0xff, d_inums__sz);
-	for (ret = ffs->eps_count; ret; --ret) {
-		struct ffs_ep *ptr;
-
-		ptr = vla_ptr(vlabuf, d, eps);
-		ptr[ret].num = -1;
-	}
+	eps_ptr = vla_ptr(vlabuf, d, eps);
+	for (i = 0; i < ffs->eps_count; i++)
+		eps_ptr[i].num = -1;
 
 	/* Save pointers
 	 * d_eps == vlabuf, func->eps used to kfree vlabuf later
@@ -2851,7 +2969,7 @@ static int _ffs_func_bind(struct usb_configuration *c,
 		goto error;
 
 	func->function.os_desc_table = vla_ptr(vlabuf, d, os_desc_table);
-	if (c->cdev->use_os_string)
+	if (c->cdev->use_os_string) {
 		for (i = 0; i < ffs->interfaces_count; ++i) {
 			struct usb_os_desc *desc;
 
@@ -2862,13 +2980,15 @@ static int _ffs_func_bind(struct usb_configuration *c,
 				vla_ptr(vlabuf, d, ext_compat) + i * 16;
 			INIT_LIST_HEAD(&desc->ext_prop);
 		}
-	ret = ffs_do_os_descs(ffs->ms_os_descs_count,
-			      vla_ptr(vlabuf, d, raw_descs) +
-			      fs_len + hs_len + ss_len,
-			      d_raw_descs__sz - fs_len - hs_len - ss_len,
-			      __ffs_func_bind_do_os_desc, func);
-	if (unlikely(ret < 0))
-		goto error;
+		ret = ffs_do_os_descs(ffs->ms_os_descs_count,
+				      vla_ptr(vlabuf, d, raw_descs) +
+				      fs_len + hs_len + ss_len,
+				      d_raw_descs__sz - fs_len - hs_len -
+				      ss_len,
+				      __ffs_func_bind_do_os_desc, func);
+		if (unlikely(ret < 0))
+			goto error;
+	}
 	func->function.os_desc_n =
 		c->cdev->use_os_string ? ffs->interfaces_count : 0;
 
diff --git a/drivers/usb/gadget/function/f_mass_storage.c b/drivers/usb/gadget/function/f_mass_storage.c
index 5c6d4d7ca605..2505117e88e8 100644
--- a/drivers/usb/gadget/function/f_mass_storage.c
+++ b/drivers/usb/gadget/function/f_mass_storage.c
@@ -2655,18 +2655,6 @@ void fsg_common_put(struct fsg_common *common)
 }
 EXPORT_SYMBOL_GPL(fsg_common_put);
 
-/* check if fsg_num_buffers is within a valid range */
-static inline int fsg_num_buffers_validate(unsigned int fsg_num_buffers)
-{
-#define FSG_MAX_NUM_BUFFERS	32
-
-	if (fsg_num_buffers >= 2 && fsg_num_buffers <= FSG_MAX_NUM_BUFFERS)
-		return 0;
-	pr_err("fsg_num_buffers %u is out of range (%d to %d)\n",
-	       fsg_num_buffers, 2, FSG_MAX_NUM_BUFFERS);
-	return -EINVAL;
-}
-
 static struct fsg_common *fsg_common_setup(struct fsg_common *common)
 {
 	if (!common) {
@@ -2709,11 +2697,7 @@ static void _fsg_common_free_buffers(struct fsg_buffhd *buffhds, unsigned n)
 int fsg_common_set_num_buffers(struct fsg_common *common, unsigned int n)
 {
 	struct fsg_buffhd *bh, *buffhds;
-	int i, rc;
-
-	rc = fsg_num_buffers_validate(n);
-	if (rc != 0)
-		return rc;
+	int i;
 
 	buffhds = kcalloc(n, sizeof(*buffhds), GFP_KERNEL);
 	if (!buffhds)
@@ -3401,10 +3385,6 @@ static ssize_t fsg_opts_num_buffers_store(struct config_item *item,
 	if (ret)
 		goto end;
 
-	ret = fsg_num_buffers_validate(num);
-	if (ret)
-		goto end;
-
 	fsg_common_set_num_buffers(opts->common, num);
 	ret = len;
 
diff --git a/drivers/usb/gadget/function/f_printer.c b/drivers/usb/gadget/function/f_printer.c
index c45104e3a64b..64706a789580 100644
--- a/drivers/usb/gadget/function/f_printer.c
+++ b/drivers/usb/gadget/function/f_printer.c
@@ -161,14 +161,6 @@ static struct usb_endpoint_descriptor hs_ep_out_desc = {
 	.wMaxPacketSize =	cpu_to_le16(512)
 };
 
-static struct usb_qualifier_descriptor dev_qualifier = {
-	.bLength =		sizeof(dev_qualifier),
-	.bDescriptorType =	USB_DT_DEVICE_QUALIFIER,
-	.bcdUSB =		cpu_to_le16(0x0200),
-	.bDeviceClass =		USB_CLASS_PRINTER,
-	.bNumConfigurations =	1
-};
-
 static struct usb_descriptor_header *hs_printer_function[] = {
 	(struct usb_descriptor_header *) &intf_desc,
 	(struct usb_descriptor_header *) &hs_ep_in_desc,
diff --git a/drivers/usb/gadget/function/f_tcm.c b/drivers/usb/gadget/function/f_tcm.c
index 35fe3c80cfc0..197f73386fac 100644
--- a/drivers/usb/gadget/function/f_tcm.c
+++ b/drivers/usb/gadget/function/f_tcm.c
@@ -1445,16 +1445,18 @@ static void usbg_drop_tpg(struct se_portal_group *se_tpg)
 	for (i = 0; i < TPG_INSTANCES; ++i)
 		if (tpg_instances[i].tpg == tpg)
 			break;
-	if (i < TPG_INSTANCES)
+	if (i < TPG_INSTANCES) {
 		tpg_instances[i].tpg = NULL;
-	opts = container_of(tpg_instances[i].func_inst,
-		struct f_tcm_opts, func_inst);
-	mutex_lock(&opts->dep_lock);
-	if (opts->has_dep)
-		module_put(opts->dependent);
-	else
-		configfs_undepend_item_unlocked(&opts->func_inst.group.cg_item);
-	mutex_unlock(&opts->dep_lock);
+		opts = container_of(tpg_instances[i].func_inst,
+			struct f_tcm_opts, func_inst);
+		mutex_lock(&opts->dep_lock);
+		if (opts->has_dep)
+			module_put(opts->dependent);
+		else
+			configfs_undepend_item_unlocked(
+				&opts->func_inst.group.cg_item);
+		mutex_unlock(&opts->dep_lock);
+	}
 	mutex_unlock(&tpg_instances_lock);
 
 	kfree(tpg);
diff --git a/drivers/usb/gadget/function/f_uac2.c b/drivers/usb/gadget/function/f_uac2.c
index 186d4b162524..cd214ec8a601 100644
--- a/drivers/usb/gadget/function/f_uac2.c
+++ b/drivers/usb/gadget/function/f_uac2.c
@@ -598,18 +598,6 @@ static struct usb_gadget_strings *fn_strings[] = {
 	NULL,
 };
 
-static struct usb_qualifier_descriptor devqual_desc = {
-	.bLength = sizeof devqual_desc,
-	.bDescriptorType = USB_DT_DEVICE_QUALIFIER,
-
-	.bcdUSB = cpu_to_le16(0x200),
-	.bDeviceClass = USB_CLASS_MISC,
-	.bDeviceSubClass = 0x02,
-	.bDeviceProtocol = 0x01,
-	.bNumConfigurations = 1,
-	.bRESERVED = 0,
-};
-
 static struct usb_interface_assoc_descriptor iad_desc = {
 	.bLength = sizeof iad_desc,
 	.bDescriptorType = USB_DT_INTERFACE_ASSOCIATION,
@@ -1292,6 +1280,7 @@ in_rq_cur(struct usb_function *fn, const struct usb_ctrlrequest *cr)
 
 	if (control_selector == UAC2_CS_CONTROL_SAM_FREQ) {
 		struct cntrl_cur_lay3 c;
+		memset(&c, 0, sizeof(struct cntrl_cur_lay3));
 
 		if (entity_id == USB_IN_CLK_ID)
 			c.dCUR = p_srate;
diff --git a/drivers/usb/gadget/function/storage_common.c b/drivers/usb/gadget/function/storage_common.c
index d62683017cf3..990df221c629 100644
--- a/drivers/usb/gadget/function/storage_common.c
+++ b/drivers/usb/gadget/function/storage_common.c
@@ -83,9 +83,7 @@ EXPORT_SYMBOL_GPL(fsg_fs_function);
  * USB 2.0 devices need to expose both high speed and full speed
  * descriptors, unless they only run at full speed.
  *
- * That means alternate endpoint descriptors (bigger packets)
- * and a "device qualifier" ... plus more construction options
- * for the configuration descriptor.
+ * That means alternate endpoint descriptors (bigger packets).
  */
 struct usb_endpoint_descriptor fsg_hs_bulk_in_desc = {
 	.bLength =		USB_DT_ENDPOINT_SIZE,
diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
index 3580f198df8b..6ded6345cd09 100644
--- a/drivers/usb/gadget/function/u_serial.c
+++ b/drivers/usb/gadget/function/u_serial.c
@@ -907,7 +907,6 @@ static int gs_write(struct tty_struct *tty, const unsigned char *buf, int count)
 {
 	struct gs_port	*port = tty->driver_data;
 	unsigned long	flags;
-	int		status;
 
 	pr_vdebug("gs_write: ttyGS%d (%p) writing %d bytes\n",
 			port->port_num, tty, count);
@@ -917,7 +916,7 @@ static int gs_write(struct tty_struct *tty, const unsigned char *buf, int count)
 		count = gs_buf_put(&port->port_write_buf, buf, count);
 	/* treat count == 0 as flush_chars() */
 	if (port->port_usb)
-		status = gs_start_tx(port);
+		gs_start_tx(port);
 	spin_unlock_irqrestore(&port->port_lock, flags);
 
 	return count;