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Unable to parse STMT_EXECUTE larger than 16MB #1350

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gfloyd opened this issue Jan 25, 2018 · 4 comments
Closed

Unable to parse STMT_EXECUTE larger than 16MB #1350

gfloyd opened this issue Jan 25, 2018 · 4 comments

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@gfloyd
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gfloyd commented Jan 25, 2018

Version:

ProxySQL version 1.4.5-19-g3b9e408, codename Truls

OS: Ubuntu 16.04

We're encountering frequent crashes with the following error:

#0  mysql_decode_length (ptr=0x6c6ce4be07903c55 <error: Cannot access memory at address 0x6c6ce4be07903c55>, len=0x7f75e1e07800) at MySQL_Protocol.cpp:203

Unfortunately, I can't seem to reproduce it reliably, as it's only happening under production load. Let me know where to send a core dump if that helps!
@renecannao
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Can you please compress few core dumps, upload them to Dropbox / Box / Google Drive, and share a link?
You can send me link via email if you prefer.
Thanks

@gfloyd
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gfloyd commented Jan 25, 2018

Link sent via email.

@renecannao renecannao changed the title 1.4.5 seg fault Unable to parse STMT_EXECUTE larger than 16MB Jan 26, 2018
@renecannao
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Thank you very much for the core dumps, it absolutely helped!
I confirm the bug, and changed the subject of this issue to better describe the problem.
According to MySQL Protocol, each packet cannot be larger than 16MB. If a payload is larger than 16MB, it is split into multiple packets, see documentation .
ProxySQL correctly handles COM_QUERY payloads larger than 16MB that are split across multiple packets, but is unable to handle COM_STMT_EXECUTE payload larger than 16MB (means, there is no code to handle such scenarios).
Normally libraries use COM_STMT_SEND_LONG_DATA to send large payloads, but nothing prevents to use large payload in COM_STMT_EXECUTE itself.

@renecannao renecannao mentioned this issue Jun 11, 2018
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renecannao added a commit that referenced this issue Jan 14, 2019
@renecannao
Wrong decoding causes crash #1350
c1c0617 
Wrong decoding in MySQL protocol for field bigger than 16MB causes crash.
The only code path affected by this seems to be reading parameters from
prepared statements.
renecannao added a commit that referenced this issue Jan 14, 2019
@renecannao
Wrong decoding causes crash #1350
b02598e 
Wrong decoding in MySQL protocol for field bigger than 16MB causes crash.
The only code path affected by this seems to be reading parameters from
prepared statements.
@renecannao
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Fixed in 1.4.14 and 2.0.0

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@gfloyd @renecannao