treehouse
/
mastodon
21
8
Fork 5
Code Issues 32 Pull Requests Projects 1 Releases Wiki Activity

blurhash_transcoder: prevent out-of-bound reads with <8bpp images (#20388) 

The Blurhash library used by Mastodon requires an input encoded as 24
bits raw RGB data. The conversion to raw RGB using Imagemagick did not
previously specify the desired bit depth. In some situations, this leads
Imagemagick to output in a pixel format using less bpp than expected.
This then manifested as segfaults of the Sidekiq process due to
out-of-bounds read, or potentially a (highly noisy) memory infoleak.

Fixes #19235.
remotes/1705712285054221092/tmp_refs/heads/main^2
Pierre Bourdon 2022-11-11 07:45:16 +01:00 committed by GitHub
parent 73fecc3358
commit 36bc90e8aa
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 1 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
lib/paperclip/blurhash_transcoder.rb
View File

@ -5,7 +5,7 @@ module Paperclip
def make
return @file unless options[:style] == :small || options[:blurhash]
pixels = convert(':source RGB:-', source: File.expand_path(@file.path)).unpack('C*')
pixels = convert(':source -depth 8 RGB:-', source: File.expand_path(@file.path)).unpack('C*')
geometry = options.fetch(:file_geometry_parser).from_file(@file)
attachment.instance.blurhash = Blurhash.encode(geometry.width, geometry.height, pixels, **(options[:blurhash] || {}))