From b249717db8ced250a586385f06e61cf7107d5222 Mon Sep 17 00:00:00 2001
From: Jeremy Harris <jgh146exb@wizmail.org>
Date: Fri, 18 Feb 2022 15:45:37 +0000
Subject: [PATCH] Specific check for null pointer

---
 src/smtp_out.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/smtp_out.c b/src/smtp_out.c
index 608a781eb..fc1e6cecd 100644
--- a/src/smtp_out.c
+++ b/src/smtp_out.c
@@ -524,13 +524,21 @@ flush_buffer(smtp_outblock * outblock, int mode)
 int rc;
 int n = outblock->ptr - outblock->buffer;
 BOOL more = mode == SCMD_MORE;
+client_conn_ctx * cctx;
 
 HDEBUG(D_transport|D_acl) debug_printf_indent("cmd buf flush %d bytes%s\n", n,
   more ? " (more expected)" : "");
 
+if (!(cctx = outblock->cctx))
+  {
+  log_write(0, LOG_MAIN|LOG_PANIC, "null conn-context pointer");
+  errno = 0;
+  return FALSE;
+  }
+
 #ifndef DISABLE_TLS
-if (outblock->cctx->tls_ctx)
-  rc = tls_write(outblock->cctx->tls_ctx, outblock->buffer, n, more);
+if (cctx->tls_ctx)		/*XXX have seen a null cctx here, rvfy sending QUIT, hence check above */
+  rc = tls_write(cctx->tls_ctx, outblock->buffer, n, more);
 else
 #endif
 
@@ -544,7 +552,7 @@ else
     requirement: TFO with data can, in rare cases, replay the data to the
     receiver. */
 
-    if (  (outblock->cctx->sock = smtp_connect(outblock->conn_args, &early_data))
+    if (  (cctx->sock = smtp_connect(outblock->conn_args, &early_data))
        < 0)
       return FALSE;
     outblock->conn_args = NULL;
@@ -552,7 +560,7 @@ else
     }
   else
     {
-    rc = send(outblock->cctx->sock, outblock->buffer, n,
+    rc = send(cctx->sock, outblock->buffer, n,
 #ifdef MSG_MORE
 	      more ? MSG_MORE : 0
 #else
@@ -567,7 +575,7 @@ else
     https://bugzilla.redhat.com/show_bug.cgi?id=1803806 */
 
     if (!more)
-      setsockopt(outblock->cctx->sock, IPPROTO_TCP, TCP_CORK, &off, sizeof(off));
+      setsockopt(cctx->sock, IPPROTO_TCP, TCP_CORK, &off, sizeof(off));
 #endif
     }
   }
-- 
2.34.1