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Fix infinite loops in copy propagation optimizer #876

Merged
merged 1 commit into from
Oct 31, 2020
Merged

Fix infinite loops in copy propagation optimizer #876

merged 1 commit into from
Oct 31, 2020

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jacob-baines
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I came across a couple of infinite loops in copy_propagation_optimizer.cpp using the attach file.

sslvpnd.zip

The sslvpnd binary should have a sha256sum of 856b68307d53d0f20f5c4a91aefc3146382e4e4210c758655d53135669642557 or you can find the binary embedded in this firmware.

The infinite loop(s) can be reproduced by fetching retdec master from Github, compiling, and executing retdec-decompiler:

albinolobster@ubuntu:~/retdec/build$ retdec-decompiler ~/sslvpnd

After a couple of minutes, retdec drops into an infinite. The issue appears to be similar to 55d46b5f3a4a5ec038ab33331926a195c7f33250, in that copy_progragation_optimizer is walking backwards through statements that loop. I followed a similar solution as introduced in the previous commit, basically exiting the loop if we see the same statement twice. With this change, sslvpnd is successfully processed after approximately 5 minutes.

I looked at the style guide and I'm not 100% my for loop line break is okay or not. Happy to fix if needed.

@s3rvac
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s3rvac commented Oct 31, 2020

Hi, thanks for the contribution 👍 Let me run TeamCity tests to see if everything passes after the fix.

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All tests pass and the fix LGTM, so I am going to merge the PR. Thanks again!

@s3rvac s3rvac merged commit 9516741 into avast:master Oct 31, 2020
s3rvac added a commit that referenced this pull request Oct 31, 2020
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2 participants