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diff --git a/src/applications/files/PhabricatorImageTransformer.php b/src/applications/files/PhabricatorImageTransformer.php
--- a/src/applications/files/PhabricatorImageTransformer.php
+++ b/src/applications/files/PhabricatorImageTransformer.php
@@ -1,5 +1,9 @@
<?php
+/**
+ * @task enormous Detecting Enormous Images
+ * @task save Saving Image Data
+ */
final class PhabricatorImageTransformer {
public function executeMemeTransform(
@@ -231,6 +235,7 @@
return $scale;
}
+
private function generatePreview(PhabricatorFile $file, $size) {
$data = $file->loadFileData();
$src = imagecreatefromstring($data);
@@ -392,45 +397,7 @@
);
}
- public static function saveImageDataInAnyFormat($data, $preferred_mime = '') {
- switch ($preferred_mime) {
- case 'image/gif': // Gif doesn't support true color
- ob_start();
- imagegif($data);
- return ob_get_clean();
- break;
- case 'image/png':
- if (function_exists('imagepng')) {
- ob_start();
- imagepng($data, null, 9);
- return ob_get_clean();
- }
- break;
- }
-
- $img = null;
-
- if (function_exists('imagejpeg')) {
- ob_start();
- imagejpeg($data);
- $img = ob_get_clean();
- } else if (function_exists('imagepng')) {
- ob_start();
- imagepng($data, null, 9);
- $img = ob_get_clean();
- } else if (function_exists('imagegif')) {
- ob_start();
- imagegif($data);
- $img = ob_get_clean();
- } else {
- throw new Exception("No image generation functions exist!");
- }
-
- return $img;
- }
-
private function applyScaleWithImagemagick(PhabricatorFile $file, $dx, $dy) {
-
$img_type = $file->getMimeType();
$imagemagick = PhabricatorEnv::getEnvConfig('files.enable-imagemagick');
@@ -444,6 +411,10 @@
$x = imagesx($src);
$y = imagesy($src);
+ if (self::isEnormousGIF($x, $y)) {
+ return null;
+ }
+
$scale = min(($dx / $x), ($dy / $y), 1);
$sdx = $scale * $x;
@@ -454,17 +425,19 @@
$resized = new TempFile();
- list($err) = exec_manual(
- 'convert %s -coalesce -resize %sX%s\! %s'
- , $input, $sdx, $sdy, $resized);
+ $future = new ExecFuture(
+ 'convert %s -coalesce -resize %sX%s%s %s',
+ $input,
+ $sdx,
+ $sdy,
+ '!',
+ $resized);
- if (!$err) {
- $new_data = Filesystem::readFile($resized);
- return $new_data;
- } else {
- return null;
- }
+ // Don't spend more than 10 seconds resizing; just fail if it takes longer
+ // than that.
+ $future->setTimeout(10)->resolvex();
+ return Filesystem::readFile($resized);
}
private function applyMemeWithImagemagick(
@@ -475,15 +448,20 @@
$img_type) {
$output = new TempFile();
-
- execx('convert %s -coalesce +adjoin %s_%%09d',
+ $future = new ExecFuture(
+ 'convert %s -coalesce +adjoin %s_%s',
+ $input,
$input,
- $input);
+ '%09d');
+ $future->setTimeout(10)->resolvex();
+ $output_files = array();
for ($ii = 0; $ii < $count; $ii++) {
$frame_name = sprintf('%s_%09d', $input, $ii);
$output_name = sprintf('%s_%09d', $output, $ii);
+ $output_files[] = $output_name;
+
$frame_data = Filesystem::readFile($frame_name);
$memed_frame_data = $this->applyMemeTo(
$frame_data,
@@ -493,9 +471,186 @@
Filesystem::writeFile($output_name, $memed_frame_data);
}
- execx('convert -loop 0 %s_* %s', $output, $output);
+ $future = new ExecFuture('convert -loop 0 %Ls %s', $output_files, $output);
+ $future->setTimeout(10)->resolvex();
return Filesystem::readFile($output);
}
+/* -( Detecting Enormous Files )------------------------------------------- */
+
+
+ /**
+ * Determine if an image is enormous (too large to transform).
+ *
+ * Attackers can perform a denial of service attack by uploading highly
+ * compressible images with enormous dimensions but a very small filesize.
+ * Transforming them (e.g., into thumbnails) may consume huge quantities of
+ * memory and CPU relative to the resources required to transmit the file.
+ *
+ * In general, we respond to these images by declining to transform them, and
+ * using a default thumbnail instead.
+ *
+ * @param int Width of the image, in pixels.
+ * @param int Height of the image, in pixels.
+ * @return bool True if this image is enormous (too large to transform).
+ * @task enormous
+ */
+ public static function isEnormousImage($x, $y) {
+ // This is just a sanity check, but if we don't have valid dimensions we
+ // shouldn't be trying to transform the file.
+ if (($x <= 0) || ($y <= 0)) {
+ return true;
+ }
+
+ return ($x * $y) > (4096 * 4096);
+ }
+
+
+ /**
+ * Determine if a GIF is enormous (too large to transform).
+ *
+ * For discussion, see @{method:isEnormousImage}. We need to be more
+ * careful about GIFs, because they can also have a large number of frames
+ * despite having a very small filesize. We're more conservative about
+ * calling GIFs enormous than about calling images in general enormous.
+ *
+ * @param int Width of the GIF, in pixels.
+ * @param int Height of the GIF, in pixels.
+ * @return bool True if this image is enormous (too large to transform).
+ * @task enormous
+ */
+ public static function isEnormousGIF($x, $y) {
+ if (self::isEnormousImage($x, $y)) {
+ return true;
+ }
+
+ return ($x * $y) > (800 * 800);
+ }
+
+
+/* -( Saving Image Data )-------------------------------------------------- */
+
+
+ /**
+ * Save an image resource to a string representation suitable for storage or
+ * transmission as an image file.
+ *
+ * Optionally, you can specify a preferred MIME type like `"image/png"`.
+ * Generally, you should specify the MIME type of the original file if you're
+ * applying file transformations. The MIME type may not be honored if
+ * Phabricator can not encode images in the given format (based on available
+ * extensions), but can save images in another format.
+ *
+ * @param resource GD image resource.
+ * @param string? Optionally, preferred mime type.
+ * @return string Bytes of an image file.
+ * @task save
+ */
+ public static function saveImageDataInAnyFormat($data, $preferred_mime = '') {
+ $preferred = null;
+ switch ($preferred_mime) {
+ case 'image/gif':
+ $preferred = self::saveImageDataAsGIF($data);
+ break;
+ case 'image/png':
+ $preferred = self::saveImageDataAsPNG($data);
+ break;
+ }
+
+ if ($preferred !== null) {
+ return $preferred;
+ }
+
+ $data = self::saveImageDataAsJPG($data);
+ if ($data !== null) {
+ return $data;
+ }
+
+ $data = self::saveImageDataAsPNG($data);
+ if ($data !== null) {
+ return $data;
+ }
+
+ $data = self::saveImageDataAsGIF($data);
+ if ($data !== null) {
+ return $data;
+ }
+
+ throw new Exception(pht('Failed to save image data into any format.'));
+ }
+
+
+ /**
+ * Save an image in PNG format, returning the file data as a string.
+ *
+ * @param resource GD image resource.
+ * @return string|null PNG file as a string, or null on failure.
+ * @task save
+ */
+ private static function saveImageDataAsPNG($image) {
+ if (!function_exists('imagepng')) {
+ return null;
+ }
+
+ ob_start();
+ $result = imagepng($image, null, 9);
+ $output = ob_get_clean();
+
+ if (!$result) {
+ return null;
+ }
+
+ return $output;
+ }
+
+
+ /**
+ * Save an image in GIF format, returning the file data as a string.
+ *
+ * @param resource GD image resource.
+ * @return string|null GIF file as a string, or null on failure.
+ * @task save
+ */
+ private static function saveImageDataAsGIF($image) {
+ if (!function_exists('imagegif')) {
+ return null;
+ }
+
+ ob_start();
+ $result = imagegif($image);
+ $output = ob_get_clean();
+
+ if (!$result) {
+ return null;
+ }
+
+ return $output;
+ }
+
+
+ /**
+ * Save an image in JPG format, returning the file data as a string.
+ *
+ * @param resource GD image resource.
+ * @return string|null JPG file as a string, or null on failure.
+ * @task save
+ */
+ private static function saveImageDataAsJPG($image) {
+ if (!function_exists('imagejpeg')) {
+ return null;
+ }
+
+ ob_start();
+ $result = imagejpeg($image);
+ $output = ob_get_clean();
+
+ if (!$result) {
+ return null;
+ }
+
+ return $output;
+ }
+
+
}

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