[newlib-cygwin/main] Cygwin: if_nametoindex: fix a 'use-after-free" uncovered by gcc-14

[Corinna Vinschen]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=5e435a20b5c851ecc7bea160aaf0b9fa9aec2363

commit 5e435a20b5c851ecc7bea160aaf0b9fa9aec2363
Author:     Corinna Vinschen <corinna@vinschen.de>
AuthorDate: Thu Feb 27 12:16:45 2025 +0100
Commit:     Corinna Vinschen <corinna@vinschen.de>
CommitDate: Thu Feb 27 12:16:45 2025 +0100

    Cygwin: if_nametoindex: fix a 'use-after-free" uncovered by gcc-14
    
    Fixes: b91d38db37d8 ("Cygwin: net: Make if_nametoindex, etc. consistent with if_nameindex.")
    Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

Diff:
---
 winsup/cygwin/net.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/winsup/cygwin/net.cc b/winsup/cygwin/net.cc
index 737e494f8f4a..9d7224a21c43 100644
--- a/winsup/cygwin/net.cc
+++ b/winsup/cygwin/net.cc
@@ -2006,8 +2006,9 @@ cygwin_if_nametoindex (const char *name)
     for (pap = pa0; pap; pap = pap->Next)
       if (strcmp (name, pap->AdapterName) == 0)
 	{
+	  unsigned idx = pap->IfIndex;
 	  free (pa0);
-	  return pap->IfIndex;
+	  return idx;
 	}
   if (pa0)
     free (pa0);