Fix bogus `Event::PaymentSent` serialization

`Event::PaymentSent` serialization has a bug where we
double-serialize the payment_preimage field but do not attempt to
read it twice. This results in a failure to read `ChannelManager`s
from disk if we have a pending `Event::PaymentSent` pending
awaiting handling when we serialize.

Instead of attempting to read both versions, we opt to simply fix
the serialization, assuming it is exceedingly rare for such a
scenario to appear (and if it does, we can assist in manual
recovery).

The release notes have been updated to note this inconsistency.

Found by the chanmon_consistency fuzz target.

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 332a8e4ba00799695c340a4295029fe5d94606c1..2931466aed9d5be571b1fab9440a5ab9aa4fce47 100644 (file)
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,13 @@
+# 0.0.99 - WIP
+
+## Serialization Compatibility
+
+ * Due to a bug discovered in 0.0.98, if a `ChannelManager` is serialized on
+   version 0.0.98 while an `Event::PaymentSent` is pending processing, the
+   `ChannelManager` will fail to deserialize both on version 0.0.98 and later
+   versions. If you have such a `ChannelManager` available, a simple patch will
+   allow it to deserialize, please file an issue if you need assistance.
+
 # 0.0.98 - 2021-06-11
 
 0.0.98 should be considered a release candidate to the first alpha release of

diff --git a/lightning/src/util/events.rs b/lightning/src/util/events.rs
index 1bdbff0333a520e0aced1526272d64bb94e75c40..dbb4178fb50e4643db6e2332d0e257bab18f8e29 100644 (file)
--- a/lightning/src/util/events.rs
+++ b/lightning/src/util/events.rs
@@ -160,7 +160,6 @@ impl Writeable for Event {
                                write_tlv_fields!(writer, {
                                        (0, payment_preimage, required),
                                });
-                               payment_preimage.write(writer)?;
                        },
                        &Event::PaymentFailed { ref payment_hash, ref rejected_by_dest,
                                #[cfg(test)]