Bug #66590 [Asn->Ana]: imagewebp() doesn't pad to even length

Edit report at https://bugs.php.net/bug.php?id=66590&edit=1 ID: 66590 Updated by: cmb@php.net Reported by: hbengali at chromium dot org -Summary: libwebp version used in imagewebp is out of date +Summary: imagewebp() doesn't pad to even length -Status: Assigned +Status: Analyzed Type: Bug -Package: *Graphics related +Package: GD related -Operating System: All +Operating System: * -PHP Version: 5.5.8 +PHP Version: 5.6.11 -Assigned To: pajoye +Assigned To: cmb Block user comment: N Private report: N New Comment: Indeed, I can confirm this issue. Consider the following simple test script: <?php $im = imagecreatetruecolor(75, 75); $red = imagecolorallocate($im, 255, 0, 0); imagefilledrectangle($im, 0, 0, 74, 74, $red); imagewebp($im, __DIR__ . '/bug66590.webp'); ?> This fails to create a valid Webp image file. display (ImageMagick 6.9.1-2), for instance, reports: "insufficient image data in file [...]". The length in the RIFF chunk is given as 92 bytes, so the file size should be 100 bytes (8 bytes RIFF header size), but it's only 99 bytes. The supplied patch obviously fixes this issue. Thanks! Previous Comments: ------------------------------------------------------------------------ [2014-01-28 00:43:18] hbengali at chromium dot org Here is a proposed fix from one of the WebP developers with the disclaimer that it is untested and may have incorrect local style. diff --git a/ext/gd/libgd/webpimg.c b/ext/gd/libgd/webpimg.c index 01bef93..ca4e9bc 100644 --- a/ext/gd/libgd/webpimg.c +++ b/ext/gd/libgd/webpimg.c @@ -778,6 +778,18 @@ WebPResult WebPEncode(const uint8* Y, (chunk_size >> 16) & 255, (chunk_size >> 24) & 255 }; memcpy(*p_out, kRiffHeader, kRiffHeaderSize); + if (img_size_bytes & 1) { /* write a padding byte */ + const int new_size = *p_out_size_bytes + 1; + unsigned char* p = (unsigned char*)realloc(*p_out, new_size); + if (p == NULL) { + free(*p_out); + *p_out = NULL; + *p_out_size_bytes = 0; + return webp_failure; + } + p[new_size - 1] = 0; + *p_out_size_bytes = new_size; + } if (psnr) { *psnr = WebPGetPSNR(Y, U, V, *p_out, *p_out_size_bytes); ------------------------------------------------------------------------ [2014-01-28 00:01:40] hbengali at chromium dot org It was brought to my attention that I did not correctly describe the issue. Here is a more accurate summary of what the problem is: The code in php (libgd) uses libvpx and writes the riff manually actually. The code generates the correct even size, but neglects the padding. It's possible older versions of libwebp would decode this, but libwebp 0.4.0 does not. ------------------------------------------------------------------------ [2014-01-27 21:48:09] hbengali at chromium dot org My bad - I did not mean for this to be a bug against the documentation. Thanks for redirecting it. ------------------------------------------------------------------------ [2014-01-27 21:45:12] bjori@php.net Did you mean to file this as a bug report for the docs? Seems like this is a problem with the extension rather then the docs? ------------------------------------------------------------------------ [2014-01-27 21:33:28] hbengali at chromium dot org Description: ------------ --- From manual page: http://www.php.net/function.imagewebp --- The latest version of libwebp (0.4.0) needs to be used here. Use of the older version causes inconsistencies when rendering in browsers that use libwebp 0.4.0. For example: https://code.google.com/p/webp/issues/detail?id=185 libwebp 0.4.0 can be found here: https://code.google.com/p/webp/downloads/detail?name=libwebp-0.4.0.tar.gz&can=2&q= ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=66590&edit=1