Merge bitcoin#26395: rpc: add missing lock around chainman.ActiveTip()

f5ff3d7 rpc: add missing lock around chainman.ActiveTip() (Andrew Toth)

Pull request description:

  bitcoin#23927 seems to have missed a lock around `chainman.ActiveChain()`.

ACKs for top commit:
  aureleoules:
    ACK f5ff3d7

Tree-SHA512: 3f116ca44c1b2bc0c7042698249ea3417dfb7c0bb81158a7ceecd087f1e02baa89948f9bb7924b1757798a1691a7de6e886aa72a0a9e227c13a3f512cc59d6c9

Co-authored-by: MacroFake <falke.marco@gmail.com>

Author: knst

src/rpc/blockchain.cpp

@@ -520,7 +520,7 @@ static RPCHelpMan getblockfrompeer()
 
     // Fetching blocks before the node has syncing past their height can prevent block files from
     // being pruned, so we avoid it if the node is in prune mode.
-    if (index->nHeight > WITH_LOCK(::cs_main, return chainman.ActiveChain().Tip()->nHeight) && node::fPruneMode) {
+    if (node::fPruneMode && index->nHeight > WITH_LOCK(chainman.GetMutex(), return chainman.ActiveTip()->nHeight)) {
         throw JSONRPCError(RPC_MISC_ERROR, "In prune mode, only blocks that the node has already synced previously can be fetched from a peer");
     }