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fix(crypto): Multisig verification doesn't work for multisig sizes of multiples of 8 #11142

Merged
merged 6 commits into from
Feb 25, 2022
Merged

fix(crypto): Multisig verification doesn't work for multisig sizes of multiples of 8 #11142

merged 6 commits into from
Feb 25, 2022

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julienrbrt
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Description

Closes: #9914

NumTrueBitsBefore was getting out of bound and panicking.


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@alexanderbez alexanderbez left a comment

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How does this fix work exactly?

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julienrbrt commented Feb 10, 2022

The issue occurs when the length of a compact bit array is the size of x bytes
This is because a bit array of length 8 is represented by one byte, but we are trying to access the 9th bit (index 8). We are getting out of bound because of that, as the 9th bit should be in a 2nd byte.

This is the problem for any bit array with a length of exactly x bytes, so any multiple of 8.
As elem let us access the byte, in order to do not get out of bound we need to check that the byte we want to access exists (hence the elem < len(bA.Elems)).

As index 8 does not exist for an exact byte, returning early still gives us the right amount of true bits before the index. Fixing the issue.

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lgtm!

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@alexanderbez are we good to put automerge label here ?

@tac0turtle tac0turtle added the A:automerge Automatically merge PR once all prerequisites pass. label Feb 24, 2022
@mergify mergify bot merged commit c686634 into cosmos:master Feb 25, 2022
@julienrbrt julienrbrt deleted the compact-bit-array-fix branch February 25, 2022 10:42
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Multisig verification doesn't work for multisig sizes of multiples of 8
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