[PATCH] iphlpapi: Avoid use of uninitialized variable

[Gerald Pfeifer]

In gateway_and_prefix_addresses_alloc prefix_len isn't set in the
error case, but used unconditionally. Avoid this by initializing
upon declaration.

(Identified by GCC 12.)

Signed-off-by: Gerald Pfeifer 
---
 dlls/iphlpapi/iphlpapi_main.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/dlls/iphlpapi/iphlpapi_main.c b/dlls/iphlpapi/iphlpapi_main.c
index c94f869c9f9..720f8147476 100644
--- a/dlls/iphlpapi/iphlpapi_main.c
+++ b/dlls/iphlpapi/iphlpapi_main.c
@@ -992,7 +992,8 @@ static DWORD gateway_and_prefix_addresses_alloc( IP_ADAPTER_ADDRESSES *aa, ULONG
     struct nsi_ipv6_forward_key *key6;
     IP_ADAPTER_GATEWAY_ADDRESS *gw, **gw_next;
     IP_ADAPTER_PREFIX *prefix, **prefix_next;
-    DWORD err, count, i, prefix_len, key_size = (family == AF_INET) ? sizeof(*key4) : sizeof(*key6);
+    DWORD err, count, i, prefix_len = 0;
+    DWORD key_size = (family == AF_INET) ? sizeof(*key4) : sizeof(*key6);
     DWORD sockaddr_size = (family == AF_INET) ? sizeof(SOCKADDR_IN) : sizeof(SOCKADDR_IN6);
     SOCKADDR_INET sockaddr;
     NET_LUID *luid;

[Huw Davies]

On Thu, Jan 27, 2022 at 11:18:53PM +0100, Gerald Pfeifer wrote:
> In gateway_and_prefix_addresses_alloc prefix_len isn't set in the
> error case, but used unconditionally. Avoid this by initializing
> upon declaration.
>
> (Identified by GCC 12.)

It's actually not used unconditionally, since it's only used if
sockaddr.si_family is non-zero, in which case it will have been
initialised.

It makes more sense to zero-init where sockaddr in also initialised
since we're in a loop.

I've sent in v2.

Huw.

[Gerald Pfeifer]

On Fri, 28 Jan 2022, Huw Davies wrote:
> It's actually not used unconditionally, since it's only used if 
> sockaddr.si_family is non-zero, in which case it will have been 
> initialised.
>
> It makes more sense to zero-init where sockaddr in also initialised
> since we're in a loop.
>
> I've sent in v2.

Very cool. Thank you, Huw!

Gerald