Fix UB from unsafe uninitialized buffer slices

Creating &mut [u8] (and &[u8]) for unitialized memory is undefined
behaviour even when not actually reading the data.

Pass &mut [MaybeUninit<u8>] instead (the recv implementations should
even fulfill the bytes::buf::UninitSlice requirement of not writing
uninitialized data (to the potentially already initialized memory!).

This also bumps netlink-sys; the other crates already got bumped.

ethtool/Cargo.toml

@@ -30,7 +30,7 @@ netlink-packet-core = "0.3.0"
 netlink-packet-generic = "0.2.0"
 netlink-packet-utils = "0.4.1"
 netlink-proto = { default-features = false, version = "0.8.0" }
-netlink-sys = "0.7.0"
+netlink-sys = "0.8.0"
 thiserror = "1.0.29"
 tokio = { version = "1.0.1", features = ["rt"], optional = true}
 

netlink-packet-generic/Cargo.toml

@@ -18,4 +18,4 @@ netlink-packet-core = "0.3"
 netlink-packet-utils = "0.4"
 
 [dev-dependencies]
-netlink-sys = { path = "../netlink-sys", version = "0.7" }
+netlink-sys = { path = "../netlink-sys", version = "0.8" }

netlink-packet-generic/tests/query_family_id.rs

@@ -26,8 +26,7 @@ fn query_family_id() {
 
     socket.send(&txbuf, 0).unwrap();
 
-    let mut rxbuf = vec![0u8; 2048];
-    socket.recv(&mut rxbuf, 0).unwrap();
+    let (rxbuf, _addr) = socket.recv_from_full().unwrap();
     let rx_packet = <NetlinkMessage<GenlMessage<GenlCtrl>>>::deserialize(&rxbuf).unwrap();
 
     if let NetlinkPayload::InnerMessage(genlmsg) = rx_packet.payload {

netlink-packet-route/Cargo.toml

@@ -26,7 +26,7 @@ name = "dump_links"
 criterion = "0.3.0"
 pcap-file = "1.1.1"
 lazy_static = "1.4.0"
-netlink-sys = "0.7"
+netlink-sys = "0.8"
 
 [[bench]]
 name = "link_message"

netlink-packet-sock-diag/Cargo.toml

@@ -22,4 +22,4 @@ smallvec = "1.4.2"
 
 [dev-dependencies]
 lazy_static = "1.4.0"
-netlink-sys = "0.7"
+netlink-sys = "0.8"

netlink-proto/Cargo.toml

@@ -17,7 +17,7 @@ log = "0.4.8"
 futures = "0.3"
 tokio = { version = "1.0", default-features = false, features = ["io-util"] }
 netlink-packet-core = "0.3"
-netlink-sys = { default-features = false, version = "0.7" }
+netlink-sys = { default-features = false, version = "0.8" }
 
 [features]
 default = ["tokio_socket"]

netlink-proto/src/framed.rs

@@ -3,6 +3,7 @@ use std::{
     fmt::Debug,
     io,
     marker::PhantomData,
+    mem::MaybeUninit,
     pin::Pin,
     slice,
     task::{Context, Poll},
@@ -63,7 +64,7 @@ where
                 // memory during a recv so it's fine to turn &mut
                 // [<MaybeUninitialized<u8>>] into &mut[u8]
                 let bytes = reader.chunk_mut();
-                let bytes = slice::from_raw_parts_mut(bytes.as_mut_ptr(), bytes.len());
+                let bytes = slice::from_raw_parts_mut(bytes.as_mut_ptr() as *mut MaybeUninit<u8>, bytes.len());
                 match ready!(socket.poll_recv_from(cx, bytes)) {
                     Ok((n, addr)) => {
                         reader.advance_mut(n);

netlink-sys/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 authors = ["Corentin Henry <corentinhenry@gmail.com>"]
 name = "netlink-sys"
-version = "0.7.0"
+version = "0.8.0"  # TODO: drop this comment - already bumped version for trait changes
 edition = "2018"
 
 homepage = "https://github.com/little-dude/netlink"

netlink-sys/src/socket.rs

@@ -1,6 +1,6 @@
 use std::{
     io::{Error, Result},
-    mem,
+    mem::{self, MaybeUninit},
     os::unix::io::{AsRawFd, FromRawFd, RawFd},
 };
 
@@ -224,7 +224,7 @@ impl Socket {
     /// In datagram oriented protocols, `recv` and `recvfrom` receive normally only ONE datagram, but this seems not to
     /// be always true for netlink sockets: with some protocols like `NETLINK_AUDIT`, multiple netlink packets can be
     /// read with a single call.
-    pub fn recv_from(&self, buf: &mut [u8], flags: libc::c_int) -> Result<(usize, SocketAddr)> {
+    pub fn recv_from(&self, buf: &mut [MaybeUninit<u8>], flags: libc::c_int) -> Result<(usize, SocketAddr)> {
         // Create an empty storage for the address. Note that Rust standard library create a
         // sockaddr_storage so that it works for any address family, but here, we already know that
         // we'll have a Netlink address, so we can create the appropriate storage.
@@ -273,7 +273,7 @@ impl Socket {
 
     /// For a connected socket, `recv` reads a datagram from the socket. The sender is the remote peer the socket is
     /// connected to (see [`Socket::connect`]). See also [`Socket::recv_from`]
-    pub fn recv(&self, buf: &mut [u8], flags: libc::c_int) -> Result<usize> {
+    pub fn recv(&self, buf: &mut [MaybeUninit<u8>], flags: libc::c_int) -> Result<usize> {
         let buf_ptr = buf.as_mut_ptr() as *mut libc::c_void;
         let buf_len = buf.len() as libc::size_t;
 
@@ -288,14 +288,16 @@ impl Socket {
     /// buffer passed as argument, this method always reads a whole message, no matter its size.
     pub fn recv_from_full(&self) -> Result<(Vec<u8>, SocketAddr)> {
         // Peek
-        let mut buf = Vec::<u8>::new();
-        let (rlen, _) = self.recv_from(&mut buf, libc::MSG_PEEK | libc::MSG_TRUNC)?;
+        let (peek_len, _) = self.recv_from(&mut [], libc::MSG_PEEK | libc::MSG_TRUNC)?;
 
         // Receive
-        let mut buf = vec![0; rlen as usize];
-        let (_, addr) = self.recv_from(&mut buf, 0)?;
-
-        Ok((buf, addr))
+        let mut buf: Vec<u8> = Vec::with_capacity(peek_len);
+        unsafe {
+            let (rlen, addr) = self.recv_from(std::slice::from_raw_parts_mut(buf.as_mut_ptr() as *mut MaybeUninit<u8>, peek_len), 0)?;
+            assert_eq!(rlen, peek_len);
+            buf.set_len(peek_len);
+            Ok((buf, addr))
+        }
     }
 
     /// Send the given buffer `buf` to the remote peer with address `addr`. The supported flags are the `MSG_*` values

netlink-sys/src/tokio.rs

@@ -1,5 +1,6 @@
 use std::{
     io,
+    mem::MaybeUninit,
     os::unix::io::{AsRawFd, FromRawFd, RawFd},
     task::{Context, Poll},
 };
@@ -71,7 +72,7 @@ impl TokioSocket {
         }
     }
 
-    pub async fn recv(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+    pub async fn recv(&mut self, buf: &mut [MaybeUninit<u8>]) -> io::Result<usize> {
         poll_fn(|cx| loop {
             // Check if the socket is readable. If not,
             // AsyncFd::poll_read_ready would have arranged for the
@@ -87,7 +88,7 @@ impl TokioSocket {
         .await
     }
 
-    pub async fn recv_from(&mut self, buf: &mut [u8]) -> io::Result<(usize, SocketAddr)> {
+    pub async fn recv_from(&mut self, buf: &mut [MaybeUninit<u8>]) -> io::Result<(usize, SocketAddr)> {
         poll_fn(|cx| self.poll_recv_from(cx, buf)).await
     }
 
@@ -98,7 +99,7 @@ impl TokioSocket {
     pub fn poll_recv_from(
         &mut self,
         cx: &mut Context,
-        buf: &mut [u8],
+        buf: &mut [MaybeUninit<u8>],
     ) -> Poll<io::Result<(usize, SocketAddr)>> {
         loop {
             trace!("poll_recv_from called");