staging: vt6656: integer overflows in private_ioctl()

There are two potential integer overflows in private_ioctl() if
userspace passes in a large sList.uItem / sNodeList.uItem.  The
subsequent call to kmalloc() would allocate a small buffer, leading
to a memory corruption.

Reported-by: Dan Rosenberg <drosenberg@vsecurity.com>
Signed-off-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/staging/vt6656/ioctl.c b/drivers/staging/vt6656/ioctl.c
index 4939002..1463d76 100644 (file)
--- a/drivers/staging/vt6656/ioctl.c
+++ b/drivers/staging/vt6656/ioctl.c
@@ -295,6 +295,10 @@ int private_ioctl(PSDevice pDevice, struct ifreq *rq)
                        result = -EFAULT;
                        break;
                }
+               if (sList.uItem > (ULONG_MAX - sizeof(SBSSIDList)) / sizeof(SBSSIDItem)) {
+                       result = -EINVAL;
+                       break;
+               }
                pList = (PSBSSIDList)kmalloc(sizeof(SBSSIDList) + (sList.uItem * sizeof(SBSSIDItem)), (int)GFP_ATOMIC);
                if (pList == NULL) {
                        result = -ENOMEM;
@@ -557,6 +561,10 @@ int private_ioctl(PSDevice pDevice, struct ifreq *rq)
                        result = -EFAULT;
                        break;
                }
+               if (sNodeList.uItem > (ULONG_MAX - sizeof(SNodeList)) / sizeof(SNodeItem)) {
+                       result = -ENOMEM;
+                       break;
+               }
                pNodeList = (PSNodeList)kmalloc(sizeof(SNodeList) + (sNodeList.uItem * sizeof(SNodeItem)), (int)GFP_ATOMIC);
                if (pNodeList == NULL) {
                        result = -ENOMEM;