search

ilyakurdyukov / jpeg-quantsmooth

JPEG artifacts removal based on quantization coefficients.
GNU Lesser General Public License v2.1
245 stars 21 forks source link

division by zero in quantsmooth_block() #29

Closed Ruanxingzhi closed 9 months ago

Ruanxingzhi commented 9 months ago

A division by zero differs from https://github.com/ilyakurdyukov/jpeg-quantsmooth/issues/25 .

sample file crashes.zip

reproduce

./jpegqs ./crash1 /dev/null

debug

fix Maybe add a check, I guess.

ilyakurdyukov commented 9 months ago

How did you get these files? The quantization tables don't look valid.

Even libjpeg says it's broken: Corrupt JPEG data: 5 extraneous bytes before marker 0xdb

ilyakurdyukov commented 9 months ago

And I can't reproduce the crash, although the result is garbage (but this is ok, since the file is damaged anyway). What options are you calling jpegqs with and what version of libjpeg did you use?

ilyakurdyukov commented 9 months ago

I see, for some reason this is only on AVX2.

Ruanxingzhi commented 9 months ago

This file was discovered by fuzzing. (Seems #25 is discovered by fuzzing too)

Reproduce(Tested on Debian sid, AMD R5-2400G): 


apt install jpegqs
jpegqs ./case/crash0 /dev/null
ilyakurdyukov commented 9 months ago

Fixed in https://github.com/ilyakurdyukov/jpeg-quantsmooth/commit/045e30082fe7e9159f7f9e1a10ffbcf703a23d64 What are you trying to achieve with your fuzzing? If it's not code execution, then it can't harm anything. The only thing I might worry about is buffer overflow.

Ruanxingzhi commented 9 months ago

Thank you for the fix!

Indeed I want to obtain vulnerabilities that can lead to command execution, such as stack overflow, heap overflow, and arbitrary address writing, but I haven't found any in jpegqs :)