[PATCH] iphlpapi: Cast caddr_t to char* before doing pointer arithmetic

[Alex Henrie]

Signed-off-by: Alex Henrie 
---
Fixes https://bugs.winehq.org/show_bug.cgi?id=18164

dlls/iphlpapi/ifenum.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/dlls/iphlpapi/ifenum.c b/dlls/iphlpapi/ifenum.c
index eed1be15d1..c3abdf0e53 100644
--- a/dlls/iphlpapi/ifenum.c
+++ b/dlls/iphlpapi/ifenum.c
@@ -1013,13 +1013,13 @@ static DWORD enumIPAddresses(PDWORD pcAddresses, struct ifconf *ifc)

if (ioctlRet == 0) {
       ifPtr = ifc->ifc_buf;
-      while (ifPtr && ifPtr < ifc->ifc_buf + ifc->ifc_len) {
+      while (ifPtr && (char *)ifPtr < ifc->ifc_buf + ifc->ifc_len) {
         struct ifreq *ifr = (struct ifreq *)ifPtr;

if (ifr->ifr_addr.sa_family == AF_INET)
           numAddresses++;

-        ifPtr += ifreq_len((struct ifreq *)ifPtr);
+        ifPtr = (char *)ifPtr + ifreq_len((struct ifreq *)ifPtr);
       }
     }
     else
@@ -1074,10 +1074,10 @@ DWORD getIPAddrTable(PMIB_IPADDRTABLE *ppIpAddrTable, HANDLE heap, DWORD flags)
         ret = NO_ERROR;
         (*ppIpAddrTable)->dwNumEntries = numAddresses;
         ifPtr = ifc.ifc_buf;
-        while (!ret && ifPtr && ifPtr < ifc.ifc_buf + ifc.ifc_len) {
+        while (!ret && ifPtr && (char *)ifPtr < ifc.ifc_buf + ifc.ifc_len) {
           struct ifreq *ifr = (struct ifreq *)ifPtr;

-          ifPtr += ifreq_len(ifr);
+          ifPtr = (char *)ifPtr + ifreq_len(ifr);

if (ifr->ifr_addr.sa_family != AF_INET)
              continue;

[Simon Richter]

Hi,

On Thu, Jun 28, 2018 at 01:54:45PM +0200, Alex Henrie wrote:
> -
>  while (ifPtr && ifPtr < ifc->ifc_buf + ifc->ifc_len) {
> -
>  while (ifPtr && (char *)ifPtr < ifc->ifc_buf + ifc->ifc_len) {

Quick question: what if ifc->ifc_len == 1 ?

In this case, can I read the length field of the record, or would that
bring me out of bounds here?

Simon