From 939a7b2b1881a0658ee9f9711cf6b808aedc9f29 Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Mon, 19 Sep 2022 10:24:26 +0930
Subject: [PATCH] db/postgres: avoid memleak.

```
"label": "db/db_postgres.c:294:char[]",
"backtrace": [
  "ccan/ccan/tal/tal.c:442 (tal_alloc_)",
  "ccan/ccan/tal/tal.c:471 (tal_alloc_arr_)",
  "ccan/ccan/tal/str/str.c:91 (tal_vfmt_)",
  "ccan/ccan/tal/str/str.c:44 (tal_fmt_)",
  "db/db_postgres.c:294 (db_postgres_delete_columns)",
  "wallet/db.c:1546 (migrate_payments_scids_as_integers)",
  "wallet/db.c:986 (db_migrate)",
  "wallet/db.c:1019 (db_setup)",
  "wallet/wallet.c:101 (wallet_new)",
  "lightningd/lightningd.c:1023 (main)",
  "../csu/libc-start.c:308 (__libc_start_main)"
],
"parents": [
  "db/utils.c:317:struct db",
  "lightningd/lightningd.c:107:struct lightningd"
]
```

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
 db/db_postgres.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/db/db_postgres.c b/db/db_postgres.c
index 19ff4d52c..0d3eb7f0b 100644
--- a/db/db_postgres.c
+++ b/db/db_postgres.c
@@ -291,7 +291,7 @@ static bool db_postgres_delete_columns(struct db *db,
 {
 	char *cmd;
 
-	cmd = tal_fmt(db, "ALTER TABLE %s ", tablename);
+	cmd = tal_fmt(tmpctx, "ALTER TABLE %s ", tablename);
 	for (size_t i = 0; i < num_cols; i++) {
 		if (i != 0)
 			tal_append_fmt(&cmd, ", ");