check on PLTE: duplicate & sBIT: out of place

version

commit_hash = adc9439

description

Hi,I found that given the following png(maybe not a valid png file), libspng(commit_hash=adc9439) could successfully parse it, while libpng reports errors and warnings: libpng warning: sBIT: out of place, libpng error: PLTE: duplicate.

Meanwhile, I tried an older version of libspng (commit_hash=2a32ffa), and found that the old version does not consider the file as parsable.

I'm not sure if something introduced in a particular commit caused this issue to occur.

reproduction steps

The testcase is attached. You can use the following command to reproduce the issue:

If you need the specific parsing code to reproduce it, it can be easily reproduced from the zip below,because The compilation commands have essentially been scripted.

bugs_report.tar.gz

- prepare the path and sourse

Extract the compressed package bugs_report.tar.gz to a directory, referred to as yourpath2. Modify the file compile_commit_hash.sh and the Makefile to replace yourpath with your actual working directory.

Then, create the directories src/ and build/ in the working directory yourpath . In the src directory, execute the command https://github.com/randy408/libspng to clone the repository.

Finally, modify the file compile_commit_hash.sh to replace yourpath2 with the directory path where you extracted the compressed package.

- compile and test

In the yourpath2 directory, execute the commands:

./compile_commit_hash.sh adc9439

to compile the new versions of spng and to generate the executable files for testing

In the yourpath2 directory, execute the commands:

./compile_commit_hash.sh 2a32ffa

to compile the old versions of spng and to generate the executable files for testing.

In the yourpath2 directory, execute the commands:

./spng_Parse_adc9439 testcase.png

and

./spng_Parse_2a32ffa testcase.png

to observe the different behaviors of libspng on the same testcase.

Expected behavior

The testcase.png : should not be parsed successfully in the newest libspng version.

Platform

• OS: ubuntu22.04.05 (kernel: Linux 6.10.11)
• Compiler: clang 14.0.0
• Architecture: x86_64

Additional context

I also test it on libpng , which shows:

libpng warning: sBIT: out of place
libpng error: PLTE: duplicate

and its ret is not 0.

Thanks in advance.
Elinor