Bug 59960 - CoreIPC/ArgumentDecoder should use aligned memory for its internal copy of data
Summary: CoreIPC/ArgumentDecoder should use aligned memory for its internal copy of data
Alias: None
Product: WebKit
Classification: Unclassified
Component: WebKit2 (show other bugs)
Version: 528+ (Nightly build)
Hardware: S60 Hardware S60 3rd edition
: P2 Normal
Assignee: Siddharth Mathur
Depends on:
Blocks: 50251
  Show dependency treegraph
Reported: 2011-05-02 14:11 PDT by Siddharth Mathur
Modified: 2011-05-05 08:32 PDT (History)
4 users (show)

See Also:

Patch (3.59 KB, patch)
2011-05-03 08:22 PDT, Siddharth Mathur
andersca: review-
Details | Formatted Diff | Diff
Patch with assert and fixed Changelog (3.64 KB, patch)
2011-05-03 13:26 PDT, Siddharth Mathur
no flags Details | Formatted Diff | Diff

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Description Siddharth Mathur 2011-05-02 14:11:54 PDT
While debugging erratic page loading issues with the Symbian port of WebKit2 (patch in Bug 55877) ,  
I observed that in ArgumentDecoder::initialize(), the fastMalloc will return an arbitrarily aligned address. 
    m_buffer = static_cast<uint8_t*>(fastMalloc(bufferSize)); 

However, soon enough we attempt to unpack a uint64_t in the same function .. 

.. and call alignBufferPosition(8, 8) which leads to a check of the alignment of the base address. 

For small messages (size 9 in my case), this leads to markInvalid() being called and then bad things happen with the state of the 2 processes. 

We should consider changing the fastMalloc(bufferSize) code to a slightly larger sized allocation which guarantees sizeof(uin64_t) alignment of the base address m_buffer.
Comment 1 Siddharth Mathur 2011-05-03 08:22:04 PDT
Created attachment 92080 [details]
Comment 2 Anders Carlsson 2011-05-03 10:28:38 PDT
Comment on attachment 92080 [details]

View in context: https://bugs.webkit.org/attachment.cgi?id=92080&action=review

> Source/WebKit2/ChangeLog:1
> +2011-05-03  Siddharth Mathur  <siddharth mathur>

No e-mail address here.

> Source/WebKit2/Platform/CoreIPC/ArgumentDecoder.cpp:71
> +    m_buffer = roundUpToAlignment(m_allocatedBase, expectedAlignment);

If you want, you can assert that m_buffer is aligned here.
Comment 3 Siddharth Mathur 2011-05-03 13:26:30 PDT
Created attachment 92114 [details]
Patch with assert and fixed Changelog
Comment 4 WebKit Commit Bot 2011-05-04 09:58:11 PDT
The commit-queue encountered the following flaky tests while processing attachment 92114 [details]:

http/tests/xmlhttprequest/remember-bad-password.html bug 51733 (author: ap@webkit.org)
The commit-queue is continuing to process your patch.
Comment 5 WebKit Commit Bot 2011-05-04 09:59:39 PDT
Comment on attachment 92114 [details]
Patch with assert and fixed Changelog

Clearing flags on attachment: 92114

Committed r85755: <http://trac.webkit.org/changeset/85755>
Comment 6 WebKit Commit Bot 2011-05-04 09:59:47 PDT
All reviewed patches have been landed.  Closing bug.