From ad6012159acf18c6b5c0f4edf037e8c9a2dbc966 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sebastian=20Dr=C3=B6ge?= <sebastian@centricular.com>
Date: Wed, 18 May 2022 11:24:37 +0300
Subject: [PATCH] matroskademux: Fix integer overflows in zlib/bz2/etc
 decompression code

Various variables were of smaller types than needed and there were no
checks for any overflows when doing additions on the sizes. This is all
checked now.

In addition the size of the decompressed data is limited to 120MB now as
any larger sizes are likely pathological and we can avoid out of memory
situations in many cases like this.

Also fix a bug where the available output size on the next iteration in
the zlib/bz2 decompression code was provided too large and could
potentially lead to out of bound writes.

Thanks to Adam Doupe for analyzing and reporting the issue.

CVE: CVE-2022-1922, CVE-2022-1923, CVE-2022-1924, CVE-2022-1925

https://gstreamer.freedesktop.org/security/sa-2022-0002.html

Fixes https://gitlab.freedesktop.org/gstreamer/gstreamer/-/issues/1225

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/2610>
---
 gst/matroska/matroska-read-common.c       | 76 +++++++++++++++----
 1 file changed, 61 insertions(+), 15 deletions(-)

diff --git a/gst/matroska/matroska-read-common.c b/gst/matroska/matroska-read-common.c
index eb317644cc5..6fadbba9567 100644
--- a/gst/matroska/matroska-read-common.c
+++ b/gst/matroska/matroska-read-common.c
@@ -70,6 +70,10 @@ typedef struct
   gboolean audio_only;
 } TargetTypeContext;
 
+/* 120MB as maximum decompressed data size. Anything bigger is likely
+ * pathological, and like this we avoid out of memory situations in many cases
+ */
+#define MAX_DECOMPRESS_SIZE (120 * 1024 * 1024)
 
 static gboolean
 gst_matroska_decompress_data (GstMatroskaTrackEncoding * enc,
@@ -77,19 +81,23 @@ gst_matroska_decompress_data (GstMatroskaTrackEncoding * enc,
     GstMatroskaTrackCompressionAlgorithm algo)
 {
   guint8 *new_data = NULL;
-  guint new_size = 0;
+  gsize new_size = 0;
   guint8 *data = *data_out;
-  guint size = *size_out;
+  const gsize size = *size_out;
   gboolean ret = TRUE;
 
+  if (size > G_MAXUINT32) {
+    GST_WARNING ("too large compressed data buffer.");
+    ret = FALSE;
+    goto out;
+  }
+
   if (algo == GST_MATROSKA_TRACK_COMPRESSION_ALGORITHM_ZLIB) {
 #ifdef HAVE_ZLIB
     /* zlib encoded data */
     z_stream zstream;
-    guint orig_size;
     int result;
 
-    orig_size = size;
     zstream.zalloc = (alloc_func) 0;
     zstream.zfree = (free_func) 0;
     zstream.opaque = (voidpf) 0;
@@ -99,8 +107,8 @@ gst_matroska_decompress_data (GstMatroskaTrackEncoding * enc,
       goto out;
     }
     zstream.next_in = (Bytef *) data;
-    zstream.avail_in = orig_size;
-    new_size = orig_size;
+    zstream.avail_in = size;
+    new_size = size;
     new_data = g_malloc (new_size);
     zstream.avail_out = new_size;
     zstream.next_out = (Bytef *) new_data;
@@ -114,10 +122,18 @@ gst_matroska_decompress_data (GstMatroskaTrackEncoding * enc,
         break;
       }
 
+      if (new_size > G_MAXSIZE - 4096 || new_size + 4096 > MAX_DECOMPRESS_SIZE) {
+        GST_WARNING ("too big decompressed data");
+        result = Z_MEM_ERROR;
+        break;
+      }
+
       new_size += 4096;
       new_data = g_realloc (new_data, new_size);
       zstream.next_out = (Bytef *) (new_data + zstream.total_out);
-      zstream.avail_out += 4096;
+      /* avail_out is an unsigned int */
+      g_assert (new_size - zstream.total_out <= G_MAXUINT);
+      zstream.avail_out = new_size - zstream.total_out;
     } while (zstream.avail_in > 0);
 
     if (result != Z_STREAM_END) {
@@ -137,13 +153,11 @@ gst_matroska_decompress_data (GstMatroskaTrackEncoding * enc,
 #ifdef HAVE_BZ2
     /* bzip2 encoded data */
     bz_stream bzstream;
-    guint orig_size;
     int result;
 
     bzstream.bzalloc = NULL;
     bzstream.bzfree = NULL;
     bzstream.opaque = NULL;
-    orig_size = size;
 
     if (BZ2_bzDecompressInit (&bzstream, 0, 0) != BZ_OK) {
       GST_WARNING ("bzip2 initialization failed.");
@@ -152,8 +166,8 @@ gst_matroska_decompress_data (GstMatroskaTrackEncoding * enc,
     }
 
     bzstream.next_in = (char *) data;
-    bzstream.avail_in = orig_size;
-    new_size = orig_size;
+    bzstream.avail_in = size;
+    new_size = size;
     new_data = g_malloc (new_size);
     bzstream.avail_out = new_size;
     bzstream.next_out = (char *) new_data;
@@ -167,17 +181,31 @@ gst_matroska_decompress_data (GstMatroskaTrackEncoding * enc,
         break;
       }
 
+      if (new_size > G_MAXSIZE - 4096 || new_size + 4096 > MAX_DECOMPRESS_SIZE) {
+        GST_WARNING ("too big decompressed data");
+        result = BZ_MEM_ERROR;
+        break;
+      }
+
       new_size += 4096;
       new_data = g_realloc (new_data, new_size);
-      bzstream.next_out = (char *) (new_data + bzstream.total_out_lo32);
-      bzstream.avail_out += 4096;
+      bzstream.next_out =
+          (char *) (new_data + ((guint64) bzstream.total_out_hi32 << 32) +
+          bzstream.total_out_lo32);
+      /* avail_out is an unsigned int */
+      g_assert (new_size - ((guint64) bzstream.total_out_hi32 << 32) +
+          bzstream.total_out_lo32 <= G_MAXUINT);
+      bzstream.avail_out =
+          new_size - ((guint64) bzstream.total_out_hi32 << 32) +
+          bzstream.total_out_lo32;
     } while (bzstream.avail_in > 0);
 
     if (result != BZ_STREAM_END) {
       ret = FALSE;
       g_free (new_data);
     } else {
-      new_size = bzstream.total_out_lo32;
+      new_size =
+          ((guint64) bzstream.total_out_hi32 << 32) + bzstream.total_out_lo32;
     }
     BZ2_bzDecompressEnd (&bzstream);
 
@@ -189,7 +217,13 @@ gst_matroska_decompress_data (GstMatroskaTrackEncoding * enc,
   } else if (algo == GST_MATROSKA_TRACK_COMPRESSION_ALGORITHM_LZO1X) {
     /* lzo encoded data */
     int result;
-    int orig_size, out_size;
+    gint orig_size, out_size;
+
+    if (size > G_MAXINT) {
+      GST_WARNING ("too large compressed data buffer.");
+      ret = FALSE;
+      goto out;
+    }
 
     orig_size = size;
     out_size = size;
@@ -203,6 +237,11 @@ gst_matroska_decompress_data (GstMatroskaTrackEncoding * enc,
       result = lzo1x_decode (new_data, &out_size, data, &orig_size);
 
       if (orig_size > 0) {
+        if (new_size > G_MAXINT - 4096 || new_size + 4096 > MAX_DECOMPRESS_SIZE) {
+          GST_WARNING ("too big decompressed data");
+          result = LZO_ERROR;
+          break;
+        }
         new_size += 4096;
         new_data = g_realloc (new_data, new_size);
       }
@@ -221,6 +260,13 @@ gst_matroska_decompress_data (GstMatroskaTrackEncoding * enc,
   } else if (algo == GST_MATROSKA_TRACK_COMPRESSION_ALGORITHM_HEADERSTRIP) {
     /* header stripped encoded data */
     if (enc->comp_settings_length > 0) {
+      if (size > G_MAXSIZE - enc->comp_settings_length
+          || size + enc->comp_settings_length > MAX_DECOMPRESS_SIZE) {
+        GST_WARNING ("too big decompressed data");
+        ret = FALSE;
+        goto out;
+      }
+
       new_data = g_malloc (size + enc->comp_settings_length);
       new_size = size + enc->comp_settings_length;
 
-- 
GitLab
