fix(rdpsnd-native): allocate Opus PCM buffer as Vec<i16> to avoid alignment panic

crates/ironrdp-rdpsnd-native/src/cpal.rs

@@ -164,11 +164,19 @@ impl DecodeStream {
                             clippy::as_conversions,
                             reason = "opus::Channels has no conversions to usize implemented"
                         )]
-                        let mut pcm = vec![0u8; nb_samples * chan as usize * size_of::<i16>()];
-                        if let Err(error) = dec.decode(&pkt, bytemuck::cast_slice_mut(pcm.as_mut_slice()), false) {
+                        let mut pcm_i16 = vec![0i16; nb_samples * chan as usize];
+                        if let Err(error) = dec.decode(&pkt, &mut pcm_i16, false) {
                             error!(?error, "Failed to decode an Opus packet");
                             continue;
                         }
+                        // Vec<u8> is what the channel carries downstream. Reinterpreting
+                        // Vec<i16> -> Vec<u8> via cast_slice is safe (smaller alignment).
+                        // Allocating as Vec<i16> in the first place avoids the alignment
+                        // hazard of `bytemuck::cast_slice_mut::<u8, i16>` panicking when
+                        // the allocator hands back a u8 buffer that is not 2-byte aligned
+                        // (which manifested as a hard crash in #1202 under the burst of
+                        // malformed Opus packets generated by a server reboot).
+                        let pcm = bytemuck::cast_slice(&pcm_i16).to_vec();
 
                         if dec_tx.send(pcm).is_err() {
                             error!("Failed to send the decoded Opus packet over the channel");