ALSA: usb-audio: Fix a DMA to stack memory bug

commit f7d306b47a24367302bd4fe846854e07752ffcd9 upstream.

The usb_get_descriptor() function does DMA so we're not allowed
to use a stack buffer for that.  Doing DMA to the stack is not portable
all architectures.  Move the "new_device_descriptor" from being stored
on the stack and allocate it with kmalloc() instead.

Fixes: b909df18ce2a ("ALSA: usb-audio: Fix potential out-of-bound accesses for Extigy and Mbox devices")
Cc: stable@kernel.org
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://patch.msgid.link/60e3aa09-039d-46d2-934c-6f123026c2eb@stanley.mountain
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Benoît Sevens <bsevens@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
index 9590c16501ef68f7fb7fab88189473ef206e9550..eed155f12a1f8d622f5c198b4623a3460cd7327e 100644 (file)
--- a/sound/usb/quirks.c
+++ b/sound/usb/quirks.c
@@ -595,7 +595,7 @@ int snd_usb_create_quirk(struct snd_usb_audio *chip,
 static int snd_usb_extigy_boot_quirk(struct usb_device *dev, struct usb_interface *intf)
 {
        struct usb_host_config *config = dev->actconfig;
-       struct usb_device_descriptor new_device_descriptor;
+       struct usb_device_descriptor *new_device_descriptor = NULL;
        int err;
 
        if (le16_to_cpu(get_cfg_desc(config)->wTotalLength) == EXTIGY_FIRMWARE_SIZE_OLD ||
@@ -606,15 +606,20 @@ static int snd_usb_extigy_boot_quirk(struct usb_device *dev, struct usb_interfac
                                      0x10, 0x43, 0x0001, 0x000a, NULL, 0);
                if (err < 0)
                        dev_dbg(&dev->dev, "error sending boot message: %d\n", err);
+
+               new_device_descriptor = kmalloc(sizeof(*new_device_descriptor), GFP_KERNEL);
+               if (!new_device_descriptor)
+                       return -ENOMEM;
                err = usb_get_descriptor(dev, USB_DT_DEVICE, 0,
-                               &new_device_descriptor, sizeof(new_device_descriptor));
+                               new_device_descriptor, sizeof(*new_device_descriptor));
                if (err < 0)
                        dev_dbg(&dev->dev, "error usb_get_descriptor: %d\n", err);
-               if (new_device_descriptor.bNumConfigurations > dev->descriptor.bNumConfigurations)
+               if (new_device_descriptor->bNumConfigurations > dev->descriptor.bNumConfigurations)
                        dev_dbg(&dev->dev, "error too large bNumConfigurations: %d\n",
-                               new_device_descriptor.bNumConfigurations);
+                               new_device_descriptor->bNumConfigurations);
                else
-                       memcpy(&dev->descriptor, &new_device_descriptor, sizeof(dev->descriptor));
+                       memcpy(&dev->descriptor, new_device_descriptor, sizeof(dev->descriptor));
+               kfree(new_device_descriptor);
                err = usb_reset_configuration(dev);
                if (err < 0)
                        dev_dbg(&dev->dev, "error usb_reset_configuration: %d\n", err);
@@ -946,7 +951,7 @@ static void mbox2_setup_48_24_magic(struct usb_device *dev)
 static int snd_usb_mbox2_boot_quirk(struct usb_device *dev)
 {
        struct usb_host_config *config = dev->actconfig;
-       struct usb_device_descriptor new_device_descriptor;
+       struct usb_device_descriptor *new_device_descriptor = NULL;
        int err;
        u8 bootresponse[0x12];
        int fwsize;
@@ -981,15 +986,21 @@ static int snd_usb_mbox2_boot_quirk(struct usb_device *dev)
 
        dev_dbg(&dev->dev, "device initialised!\n");
 
+       new_device_descriptor = kmalloc(sizeof(*new_device_descriptor), GFP_KERNEL);
+       if (!new_device_descriptor)
+               return -ENOMEM;
+
        err = usb_get_descriptor(dev, USB_DT_DEVICE, 0,
-               &new_device_descriptor, sizeof(new_device_descriptor));
+               new_device_descriptor, sizeof(*new_device_descriptor));
        if (err < 0)
                dev_dbg(&dev->dev, "error usb_get_descriptor: %d\n", err);
-       if (new_device_descriptor.bNumConfigurations > dev->descriptor.bNumConfigurations)
+       if (new_device_descriptor->bNumConfigurations > dev->descriptor.bNumConfigurations)
                dev_dbg(&dev->dev, "error too large bNumConfigurations: %d\n",
-                       new_device_descriptor.bNumConfigurations);
+                       new_device_descriptor->bNumConfigurations);
        else
-               memcpy(&dev->descriptor, &new_device_descriptor, sizeof(dev->descriptor));
+               memcpy(&dev->descriptor, new_device_descriptor, sizeof(dev->descriptor));
+
+       kfree(new_device_descriptor);
 
        err = usb_reset_configuration(dev);
        if (err < 0)