From 4245d63be73402df5917bbd099178ba56c136e13 Mon Sep 17 00:00:00 2001
From: Tomas Mraz <tmraz@fedoraproject.org>
Date: Thu, 12 Sep 2019 12:27:36 +0200
Subject: [PATCH] BIO_f_zlib: Properly handle BIO_CTRL_PENDING and
 BIO_CTRL_WPENDING calls.

There can be data to write in output buffer and data to read that were
not yet read in the input stream.

Fixes #9866
---
 crypto/comp/c_zlib.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/crypto/comp/c_zlib.c b/crypto/comp/c_zlib.c
index 78219f202d8b8..3d2c142f004d9 100644
--- a/crypto/comp/c_zlib.c
+++ b/crypto/comp/c_zlib.c
@@ -546,6 +546,7 @@ static long bio_zlib_ctrl(BIO *b, int cmd, long num, void *ptr)
     int ret, *ip;
     int ibs, obs;
     BIO *next = BIO_next(b);
+    z_stream *zin;
 
     if (next == NULL)
         return 0;
@@ -598,6 +599,30 @@ static long bio_zlib_ctrl(BIO *b, int cmd, long num, void *ptr)
         BIO_copy_next_retry(b);
         break;
 
+    case BIO_CTRL_WPENDING:
+        if (ctx->obuf == NULL)
+            return 0;
+
+        if (ctx->odone) {
+            ret = ctx->ocount;
+        }
+        else {
+            ret = ctx->ocount;
+            if (ret == 0)
+                /* Unknown amount pending but we are not finished */
+                ret = 1;
+        }
+        if (ret == 0)
+            ret = BIO_ctrl(next, cmd, num, ptr);
+        break;
+
+    case BIO_CTRL_PENDING:
+        zin = &ctx->zin;
+        ret = zin->avail_in;
+        if (ret == 0)
+            ret = BIO_ctrl(next, cmd, num, ptr);
+        break;
+
     default:
         ret = BIO_ctrl(next, cmd, num, ptr);
         break;