From 4f26b4c6ff9ec3f3dbc0c0269187539eb029ca14 Mon Sep 17 00:00:00 2001
From: Uwe Klotz <uwe.klotz@slowtec.de>
Date: Thu, 21 Sep 2023 21:19:50 +0200
Subject: [PATCH] watch::Receiver::wait_for(): Prevent poisoning of the lock

---
 tokio/src/sync/watch.rs | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/tokio/src/sync/watch.rs b/tokio/src/sync/watch.rs
index fa1ad05139c..89ac6891cb4 100644
--- a/tokio/src/sync/watch.rs
+++ b/tokio/src/sync/watch.rs
@@ -772,8 +772,24 @@ impl<T> Receiver<T> {
                 let has_changed = self.version != new_version;
                 self.version = new_version;
 
-                if (!closed || has_changed) && f(&inner) {
-                    return Ok(Ref { inner, has_changed });
+                if !closed || has_changed {
+                    let result =
+                        panic::catch_unwind(panic::AssertUnwindSafe(|| f(&inner)));
+                    match result {
+                        Ok(true) => {
+                            return Ok(Ref { inner, has_changed });
+                        }
+                        Ok(false) => {
+                            // Skip the value.
+                        }
+                        Err(panicked) => {
+                            // Drop the read-lock to avoid poisoning it.
+                            drop(inner);
+                            // Forward the panic to the caller.
+                            panic::resume_unwind(panicked);
+                            // Unreachable
+                        }
+                    };
                 }
             }