There used to be an integer overflow check in proc_do_submiturb() but
it accidentally got removed. We need to put it back. The
uurb->buffer_length variable is a signed integer and it's controlled by
the user. It can lead to an integer overflow when we do:
num_sgs = DIV_ROUND_UP(uurb->buffer_length, USB_SG_SIZE);
Fixes: 1129d270cbfb ("USB: Increase usbfs transfer limit")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index 318bb3b96687..f3c9cff2101c 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -140,6 +140,9 @@ module_param(usbfs_memory_mb, uint, 0644);
MODULE_PARM_DESC(usbfs_memory_mb,
"maximum MB allowed for usbfs buffers (0 = no limit)");
+/* Hard limit, necessary to avoid arithmetic overflow */
+#define USBFS_XFER_MAX (UINT_MAX / 2 - 1000000)
+
static atomic64_t usbfs_memory_usage; /* Total memory currently allocated */
/* Check whether it's okay to allocate more memory for a transfer */
@@ -1460,6 +1463,8 @@ static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb
USBDEVFS_URB_ZERO_PACKET |
USBDEVFS_URB_NO_INTERRUPT))
return -EINVAL;
+ if (uurb->buffer_length >= USBFS_XFER_MAX)
+ return -EINVAL;
if (uurb->buffer_length > 0 && !uurb->buffer)
return -EINVAL;
if (!(uurb->type == USBDEVFS_URB_TYPE_CONTROL &&
--
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