Fix bug when parsing imports from 32bit PE. #2119
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There is a bug when parsing [1] which turns out to be incorrectly checking the number of successfully parsed imported functions and not the number of parsed attempts. This particular sample is badly malformed and is causing excessive loops in the parser while attempting to parse invalid data. With this fix it will finish in a few seconds on my laptop. [1]: 9c8e4dfa84b1ce7e919964978d33eada266d58b2aacdbef44b0618cc178ea421
plusvic
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Nov 26, 2024
plusvic
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After #2119 `yara` is consuming a large amount of memory while parsing 9bddb45c44d9c25a4f97ef800cb110de5e6a15349bac05d389c8bda37902f25a. That's because after the change it doesn't limit the total number of imported functions, only the total number of parsing attempts, but the count is reset with each import entry. This file has a large number of entries and a large number of functions per entry, the total number of functions is very high. It turns out that we must limit both the total number of correctly parsed functions (for cases like this one), and the total number of parsing attempts (for cases like the one #2119 was aiming to solve).
plusvic
added a commit
that referenced
this pull request
Nov 28, 2024
After #2119 `yara` is consuming a large amount of memory while parsing 9bddb45c44d9c25a4f97ef800cb110de5e6a15349bac05d389c8bda37902f25a. That's because after the change it doesn't limit the total number of imported functions, only the total number of parsing attempts, but the count is reset with each import entry. This file has a large number of entries and a large number of functions per entry, the total number of functions is very high. It turns out that we must limit both the total number of correctly parsed functions (for cases like this one), and the total number of parsing attempts (for cases like the one #2119 was aiming to solve).
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There is a bug when parsing 1 which turns out to be incorrectly checking the number of successfully parsed imported functions and not the number of parsed attempts. This particular sample is badly malformed and is causing excessive loops in the parser while attempting to parse invalid data. With this fix it will finish in a few seconds on my laptop.