From f46b9320ae32f00aa97a397b33eaa7abdcb47fe3 Mon Sep 17 00:00:00 2001
From: cypherpunks <cypherpunks@torproject.org>
Date: Thu, 12 Mar 2020 16:02:00 +0000
Subject: [PATCH] buf: add BUF_MAX_LEN

---
 src/core/mainloop/connection.c | 4 ++--
 src/lib/buf/buffers.h          | 3 +++
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/core/mainloop/connection.c b/src/core/mainloop/connection.c
index 708fb13cdb..f692da650d 100644
--- a/src/core/mainloop/connection.c
+++ b/src/core/mainloop/connection.c
@@ -3804,8 +3804,8 @@ connection_buf_read_from_socket(connection_t *conn, ssize_t *max_to_read,
     at_most = connection_bucket_read_limit(conn, approx_time());
   }
 
-  /* Do not allow inbuf to grow past INT_MAX - 1. */
-  const ssize_t maximum = INT_MAX - 1 - buf_datalen(conn->inbuf);
+  /* Do not allow inbuf to grow past BUF_MAX_LEN. */
+  const ssize_t maximum = BUF_MAX_LEN - buf_datalen(conn->inbuf);
   if (at_most > maximum) {
     at_most = maximum;
   }
diff --git a/src/lib/buf/buffers.h b/src/lib/buf/buffers.h
index fadd4174c0..d8a77feb72 100644
--- a/src/lib/buf/buffers.h
+++ b/src/lib/buf/buffers.h
@@ -29,6 +29,9 @@ void buf_free_(buf_t *buf);
 void buf_clear(buf_t *buf);
 buf_t *buf_copy(const buf_t *buf);
 
+/** Maximum bytes in a buffer, inclusive. */
+#define BUF_MAX_LEN (INT_MAX - 1)
+
 MOCK_DECL(size_t, buf_datalen, (const buf_t *buf));
 size_t buf_allocation(const buf_t *buf);
 size_t buf_slack(const buf_t *buf);