Imagemagick/convert can be crashed by processing an empty PNG

[Saverio Miroddi]

(I'm not sure if this classifies as security issue or not, as the crash itself is due to an assertion failure, not to a buffer overflow or similar).

When executing the command:

    convert empty.png -resize 150x150 -colors 16 -colorspace RGB -quantize RGB -depth 8 -alpha remove -alpha off -format %c histogram:info:

on an empty PNG, `convert` crashes with:

    convert: ../../magick/quantum.c:216: DestroyQuantumInfo: Assertion `quantum_info != (QuantumInfo *) NULL' failed.
    Aborted (core dumped)

I've provided an empty PNG file for testing.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: imagemagick-6.q16 8:6.9.7.4+dfsg-16ubuntu6.8
ProcVersionSignature: Ubuntu 5.3.0-1017.18~18.04.1-aws 5.3.18
Uname: Linux 5.3.0-1017-aws x86_64
ApportVersion: 2.20.9-0ubuntu7.15
Architecture: amd64
Date: Fri Jul 3 11:40:12 2020
Ec2AMI: ami-0df60f5a0d9a27a14
Ec2AMIManifest: (unknown)
Ec2AvailabilityZone: eu-west-1a
Ec2InstanceType: t3.xlarge
Ec2Kernel: unavailable
Ec2Ramdisk: unavailable
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=C.UTF-8
 SHELL=/bin/bash
SourcePackage: imagemagick
UpgradeStatus: No upgrade log present (probably fresh install)

[Leonidas S. Barbosa (leosilvab)]

Hi Saverio,

As you mentioned it's not a bug since this assert was added to to exactly that, trap that kind of situation.

Thanks!

[Saverio Miroddi (64kramsystem)]

Wouldn't it be better to exit with an error message, rather than panicking? Panicking seems very drastic.