[jira] Commented: (DERBY-4088) DDMReader readBytes ArrayIndexOutOfBoundsException

["Knut Anders Hatlen (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DERBY-4088?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12680461#action_12680461 ] 

Knut Anders Hatlen commented on DERBY-4088:
-------------------------------------------

Thanks for the bug report. If possible, could you also provide step-by-step description of how to reproduce the bug? The stack trace of the ArrayIndexOutOfBoundsException would also be helpful.

I haven't been able to reproduce the bug myself, so I can't say if the patch is correct. My understanding of that code is that the check against MAX_DSS_LENGTH is used to determine the format of the byte string, which should not be affected by the current position in the read buffer. It is the call to ensureBLayerDataInBuffer() that is supposed to ensure that the read buffer is large enough and prevent that the AIOOBE is thrown. So my initial reaction is that the bug is probably somewhere else.

> DDMReader readBytes ArrayIndexOutOfBoundsException
> --------------------------------------------------
>
>                 Key: DERBY-4088
>                 URL: https://issues.apache.org/jira/browse/DERBY-4088
>             Project: Derby
>          Issue Type: Bug
>          Components: Network Server
>    Affects Versions: 10.4.2.0
>         Environment: CentOS 5, java 1.6.0_11
>            Reporter: Urban Widmark
>         Attachments: derby-ddm.patch
>
>
> DDMReader.readBytes(int length) checks the length vs DssConstants.MAX_DSS_LENGTH, but ignores the fact that the buffer position "pos" might not be 0. If pos is non-zero then the pos + length can be larger than the size of "buffer" causing an ArrayIndexOutOfBoundsException.
> For me this happened when sending a BLOB that was 32766 bytes long. The value of pos was 2 in that method.

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