Merge pull request #4172 from TheBlueMatt/2025-10-duration-deser-panic

Fix panic when deserializing `Duration`

Author: tnull

lightning/src/util/ser.rs

@@ -1688,7 +1688,14 @@ impl Readable for Duration {
 fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 let secs = Readable::read(r)?;
 let nanos = Readable::read(r)?;
-Ok(Duration::new(secs, nanos))
+// Duration::new panics if the nanosecond part in excess of a second, added to the second
+// part, overflows. To ensure this won't happen, we simply reject any case where there are
+// nanoseconds in excess of a second, which is invalid anyway.
+if nanos >= 1_000_000_000 {
+Err(DecodeError::InvalidValue)
+} else {
+Ok(Duration::new(secs, nanos))
+}
 }
 }