[PATCH] Staging: bcm: Fix an integer overflow in IOCTL_BCM_NVM_READ/WRITE

[Kevin McKinney]

Variables stNVMReadWrite.uioffset and stNVMReadWrite.uiNumBytes
are chosen from userspace and can be very high. The sum of
these two digits would result in a small number. Therefore,
this patch verifies a negative number was not entered, and
reorganizes the equation to remove the integer overflow.

Signed-off-by: Kevin McKinney <klmckinney1 at gmail.com>
---
 drivers/staging/bcm/Bcmchar.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/drivers/staging/bcm/Bcmchar.c b/drivers/staging/bcm/Bcmchar.c
index 179707b..8bf3f57 100644
--- a/drivers/staging/bcm/Bcmchar.c
+++ b/drivers/staging/bcm/Bcmchar.c
@@ -1302,8 +1302,10 @@ cntrlEnd:
 		/*
 		 * Deny the access if the offset crosses the cal area limit.
 		 */
+		if (stNVMReadWrite.uiNumBytes > Adapter->uiNVMDSDSize)
+			return STATUS_FAILURE;
 
-		if ((stNVMReadWrite.uiOffset + stNVMReadWrite.uiNumBytes) > Adapter->uiNVMDSDSize) {
+		if (stNVMReadWrite.uiOffset > Adapter->uiNVMDSDSize - stNVMReadWrite.uiNumBytes) {
 			/* BCM_DEBUG_PRINT(Adapter,DBG_TYPE_PRINTK, 0, 0,"Can't allow access beyond NVM Size: 0x%x 0x%x\n", stNVMReadWrite.uiOffset, stNVMReadWrite.uiNumBytes); */
 			return STATUS_FAILURE;
 		}
-- 
1.7.4.1