Fix improper pointer provenance

`&mut buffer[0] as *mut u8` will create a raw pointer that is only
allowed to access the very first byte of `buffer`. `slice::as_mut_ptr`
is preferred.

1 files changed, 6 insertions, 2 deletions

diff --git a/talpid-core/src/dns/windows/tcpip.rs b/talpid-core/src/dns/windows/tcpip.rs
index 70bb4660d6..3e0a8ea6e1 100644
--- a/talpid-core/src/dns/windows/tcpip.rs
+++ b/talpid-core/src/dns/windows/tcpip.rs
@@ -164,8 +164,12 @@ fn flush_dns_cache() -> Result<(), Error> {
 /// Obtain a string representation for a GUID object.
 fn string_from_guid(guid: &GUID) -> String {
     let mut buffer = [0u16; 40];
-    let length = unsafe { StringFromGUID2(guid, &mut buffer[0] as *mut _, buffer.len() as i32 - 1) }
-        as usize;
+
+    let length =
+        // SAFETY: `guid` and `buffer` are valid references.
+        // StringFromGUID2 won't write past the end of the provided length.
+        unsafe { StringFromGUID2(guid, buffer.as_mut_ptr(), buffer.len() as i32 - 1) } as usize;
+
     // cannot fail because `buffer` is large enough
     assert!(length > 0);
     let length = length - 1;