RFR: 8313765: Invalid CEN header (invalid zip64 extra data field size) [v2]

[Sergey Bylokhov]

On Mon, 14 Aug 2023 18:22:27 GMT, Lance Andersen <lancea at openjdk.org> wrote:

>> src/jdk.zipfs/share/classes/jdk/nio/zipfs/ZipFileSystem.java line 3108:
>> 
>>> 3106:                         break;
>>> 3107:                     }
>>> 3108:                     if (size == ZIP64_MINVAL) {
>> 
>> Note that we always increase "pos" only in case of "_MINVAL". If the values of size and csize are correct/valid in the "body" of the zip file and only locoff is negative then we should skip two fields in the extra block and read the third one. Otherwise, we may read some random values and throw an exception.
>
> I am not sure I (quite) understand your question completely..
> 
> How ZIpFS::readExtra  has navigated these fields has not changed
> 
>  If you have a tool that creates a zip/jar that demonstrates an issue that might need further examination, please provide a test case, the tool that created the zip/jar in question and open a new bug.

The 8302483 changed this code to throw an exception, this is why I am looking into it.
You can compare the code in this file and the same code in the ZipFile in the checkZip64ExtraFieldValues method or the code in the ZipEntry#setExtra0, where we do not increase the "off" but instead checks for "off+8" or "off + 16". So if we need to read only the third field we should read "pos+16" but for the current implementation we will read it at "pos+0" since the pos was not bumped by the code for two other fields.

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PR Review Comment: https://git.openjdk.org/jdk/pull/15273#discussion_r1293844319