Merge pull request #86 from kjdev/fix/heap-use-after-free

fix: heap-use-after-free in php_brotli_decompress_read

Author: kjdev

brotli.c

@@ -797,6 +797,7 @@ typedef struct _php_brotli_stream_data {
     php_brotli_context ctx;
     BrotliDecoderResult result;
     php_stream *stream;
+    uint8_t *input_buf;
 } php_brotli_stream_data;
 
 #define STREAM_DATA_FROM_STREAM() \
@@ -822,6 +823,10 @@ static int php_brotli_decompress_close(php_stream *stream,
 
     php_brotli_context_close(&self->ctx);
 
+    if (self->input_buf) {
+        efree(self->input_buf);
+    }
+
     efree(self);
 
     stream->abstract = NULL;
@@ -845,48 +850,33 @@ static ssize_t php_brotli_decompress_read(php_stream *stream,
     STREAM_DATA_FROM_STREAM();
 
     /* input */
-    uint8_t *input = (uint8_t *)emalloc(PHP_BROTLI_BUFFER_SIZE);
-    if (!input) {
-#if PHP_VERSION_ID < 70400
-        return 0;
-#else
-        return -1;
-#endif
+    if (!self->input_buf) {
+        self->input_buf = emalloc(PHP_BROTLI_BUFFER_SIZE);
     }
 
     if (self->result == BROTLI_DECODER_RESULT_NEEDS_MORE_INPUT) {
         if (php_stream_eof(self->stream)) {
             /* corrupt input */
-            efree(input);
 #if PHP_VERSION_ID < 70400
             return 0;
 #else
             return -1;
 #endif
         }
-        self->ctx.available_in = php_stream_read(self->stream, input,
+        self->ctx.available_in = php_stream_read(self->stream, self->input_buf,
                                                  PHP_BROTLI_BUFFER_SIZE);
         if (!self->ctx.available_in) {
-            efree(input);
 #if PHP_VERSION_ID < 70400
             return 0;
 #else
             return -1;
 #endif
         }
-        self->ctx.next_in = input;
+        self->ctx.next_in = self->input_buf;
     }
 
     /* output */
     uint8_t *output = (uint8_t *)emalloc(count);
-    if (!output) {
-        efree(input);
-#if PHP_VERSION_ID < 70400
-        return 0;
-#else
-        return -1;
-#endif
-    }
     self->ctx.available_out = count;
     self->ctx.next_out = output;
 
@@ -912,15 +902,15 @@ static ssize_t php_brotli_decompress_read(php_stream *stream,
                 break;
             }
             self->ctx.available_in = php_stream_read(self->stream,
-                                                     input, count);
-            self->ctx.next_in = input;
+                                                     self->input_buf,
+                                                     PHP_BROTLI_BUFFER_SIZE);
+            self->ctx.next_in = self->input_buf;
         } else {
             /* decoder error */
             break;
         }
     }
 
-    efree(input);
     efree(output);
 
     return ret;

tests/streams_007.phpt

@@ -0,0 +1,42 @@
+--TEST--
+compress.brotli streams read with chunk size exceeding internal buffer
+--FILE--
+<?php
+$file = dirname(__FILE__) . '/streams_007.out';
+
+// PHP_BROTLI_BUFFER_SIZE is 1 << 19 (524288). Use a payload that does not
+// compress (so the on-disk size also exceeds the internal buffer) and a read
+// chunk larger than that, exercising the NEEDS_MORE_INPUT path with
+// count > PHP_BROTLI_BUFFER_SIZE.
+$chunk = 1024 * 1024; // 1 MiB > 524288
+$data = random_bytes(1024 * 1024); // uncompressible payload
+var_dump(strlen($data) > 524288);
+
+echo "Compress\n";
+$dst = fopen('compress.brotli://' . $file, 'wb');
+var_dump(fwrite($dst, $data) === strlen($data));
+var_dump(fclose($dst));
+var_dump(filesize($file) > 524288);
+
+echo "Decompress\n";
+$fp = fopen('compress.brotli://' . $file, 'rb');
+stream_set_chunk_size($fp, $chunk);
+$out = stream_get_contents($fp);
+var_dump(fclose($fp));
+var_dump(strlen($out) === strlen($data));
+var_dump($out === $data);
+
+@unlink($file);
+?>
+===DONE===
+--EXPECTF--
+bool(true)
+Compress
+bool(true)
+bool(true)
+bool(true)
+Decompress
+bool(true)
+bool(true)
+bool(true)
+===DONE===