ALSA: usb-audio: Fix potential out-of-bound accesses for Extigy and Mbox devices

A bogus device can provide a bNumConfigurations value that exceeds the
initial value used in usb_get_configuration for allocating dev->config.

This can lead to out-of-bounds accesses later, e.g. in
usb_destroy_configuration.

Signed-off-by: Benoît Sevens <bsevens@google.com>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@kernel.org
Link: https://patch.msgid.link/20241120124144.3814457-1-bsevens@google.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
index cbfbb064a9c23ea96078eb028822bbf7f51cda2d..8bc959b60be3b66b8045081e89a41fc5eb5f23bc 100644 (file)
--- a/sound/usb/quirks.c
+++ b/sound/usb/quirks.c
@@ -555,6 +555,7 @@ 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;
        int err;
 
        if (le16_to_cpu(get_cfg_desc(config)->wTotalLength) == EXTIGY_FIRMWARE_SIZE_OLD ||
@@ -566,10 +567,14 @@ static int snd_usb_extigy_boot_quirk(struct usb_device *dev, struct usb_interfac
                if (err < 0)
                        dev_dbg(&dev->dev, "error sending boot message: %d\n", err);
                err = usb_get_descriptor(dev, USB_DT_DEVICE, 0,
-                               &dev->descriptor, sizeof(dev->descriptor));
-               config = dev->actconfig;
+                               &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)
+                       dev_dbg(&dev->dev, "error too large bNumConfigurations: %d\n",
+                               new_device_descriptor.bNumConfigurations);
+               else
+                       memcpy(&dev->descriptor, &new_device_descriptor, sizeof(dev->descriptor));
                err = usb_reset_configuration(dev);
                if (err < 0)
                        dev_dbg(&dev->dev, "error usb_reset_configuration: %d\n", err);
@@ -901,6 +906,7 @@ 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;
        int err;
        u8 bootresponse[0x12];
        int fwsize;
@@ -936,10 +942,14 @@ static int snd_usb_mbox2_boot_quirk(struct usb_device *dev)
        dev_dbg(&dev->dev, "device initialised!\n");
 
        err = usb_get_descriptor(dev, USB_DT_DEVICE, 0,
-               &dev->descriptor, sizeof(dev->descriptor));
-       config = dev->actconfig;
+               &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)
+               dev_dbg(&dev->dev, "error too large bNumConfigurations: %d\n",
+                       new_device_descriptor.bNumConfigurations);
+       else
+               memcpy(&dev->descriptor, &new_device_descriptor, sizeof(dev->descriptor));
 
        err = usb_reset_configuration(dev);
        if (err < 0)
@@ -1249,6 +1259,7 @@ static void mbox3_setup_defaults(struct usb_device *dev)
 static int snd_usb_mbox3_boot_quirk(struct usb_device *dev)
 {
        struct usb_host_config *config = dev->actconfig;
+       struct usb_device_descriptor new_device_descriptor;
        int err;
        int descriptor_size;
 
@@ -1262,10 +1273,14 @@ static int snd_usb_mbox3_boot_quirk(struct usb_device *dev)
        dev_dbg(&dev->dev, "MBOX3: device initialised!\n");
 
        err = usb_get_descriptor(dev, USB_DT_DEVICE, 0,
-               &dev->descriptor, sizeof(dev->descriptor));
-       config = dev->actconfig;
+               &new_device_descriptor, sizeof(new_device_descriptor));
        if (err < 0)
                dev_dbg(&dev->dev, "MBOX3: error usb_get_descriptor: %d\n", err);
+       if (new_device_descriptor.bNumConfigurations > dev->descriptor.bNumConfigurations)
+               dev_dbg(&dev->dev, "MBOX3: error too large bNumConfigurations: %d\n",
+                       new_device_descriptor.bNumConfigurations);
+       else
+               memcpy(&dev->descriptor, &new_device_descriptor, sizeof(dev->descriptor));
 
        err = usb_reset_configuration(dev);
        if (err < 0)