@ -16,7 +16,7 @@ This is a post-mortem concerning the minority split that occurred on Ethereum ma
### 2021-08-17 RETURNDATA corruption via datacopy
### 2021-08-17 RETURNDATA corruption via datacopy
On 2021-08-17, Guido Vranken submitted a report to bounty@ethereum.org. This co-incided with a geth-meetup in Berlin, so the geth team could fairly quickly analyse the issue.
On 2021-08-17, Guido Vranken submitted a report to bounty@ethereum.org. This coincided with a geth-meetup in Berlin, so the geth team could fairly quickly analyse the issue.
He submitted a proof of concept which called the `dataCopy` precompile, where the input slice and output slice were overlapping but shifted. Doing a `copy` where the `src` and `dest` overlaps is not a problem in itself, however, the `returnData`slice was _also_ using the same memory as a backing-array.
He submitted a proof of concept which called the `dataCopy` precompile, where the input slice and output slice were overlapping but shifted. Doing a `copy` where the `src` and `dest` overlaps is not a problem in itself, however, the `returnData`slice was _also_ using the same memory as a backing-array.