les: fix serverHandler crash after setHead (#24200)

holiman · web-flow · commit 335914a63afa · 2022-01-05T16:40:45.000+01:00
diff --git a/les/server_handler.go b/les/server_handler.go
@@ -421,7 +421,10 @@ func (h *serverHandler) broadcastLoop() {
 			}
 			var reorg uint64
 			if lastHead != nil {
-				reorg = lastHead.Number.Uint64() - rawdb.FindCommonAncestor(h.chainDb, header, lastHead).Number.Uint64()
+				// If a setHead has been performed, the common ancestor can be nil.
+				if ancestor := rawdb.FindCommonAncestor(h.chainDb, header, lastHead); ancestor != nil {
+					reorg = lastHead.Number.Uint64() - ancestor.Number.Uint64()
+				}
 			}
 			lastHead, lastTd = header, td
 			log.Debug("Announcing block to peers", "number", number, "hash", hash, "td", td, "reorg", reorg)

Original file line number	Diff line number	Diff line change
`@@ -421,7 +421,10 @@ func (h *serverHandler) broadcastLoop() {`
`421`	`421`	`}`
`422`	`422`	`var reorg uint64`
`423`	`423`	`if lastHead != nil {`
`424`		`- reorg = lastHead.Number.Uint64() - rawdb.FindCommonAncestor(h.chainDb, header, lastHead).Number.Uint64()`
	`424`	`+ // If a setHead has been performed, the common ancestor can be nil.`
	`425`	`+ if ancestor := rawdb.FindCommonAncestor(h.chainDb, header, lastHead); ancestor != nil {`
	`426`	`+ reorg = lastHead.Number.Uint64() - ancestor.Number.Uint64()`
	`427`	`+ }`
`425`	`428`	`}`
`426`	`429`	`lastHead, lastTd = header, td`
`427`	`430`	`log.Debug("Announcing block to peers", "number", number, "hash", hash, "td", td, "reorg", reorg)`