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Re: your malloc patches
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From:
Jarkko Hietaniemi
Date:
June 20, 2003 03:20
Subject:
Re: your malloc patches
Message ID:
20030620102036.GQ426218@kosh.hut.fi
> Well, you said you tested it on other 64bit stuff; and you said that
That was a false result: the IRIX explicitly always disables mymalloc.
> If it is really bugs in malloc.c, then it is the pair of
> fill()/check() which is failing. The test above would give some info
> *which* one of these two steps fails. The target is to have memory
> 0xDEADBEEF-filled (4-byte-aligned). And if any malloc() was done with
> this memory, it should have 4 0x55 bytes before the region, and >=4
> 0x55 bytes after the region (up to 4-byte aligned boundary; actually,
> on 64-bit machines it may have been 0x55 0x55 0x55 0x55 0x00 0x00 0x00
> 0x00 or 0x00 0x00 0x00 0x00 0x55 0x55 0x55 0x55 instead of 4 0x55
> bytes).
It seems that the cmp_pat_4bytes() is being called with
s = 0x140012040 = "^D\377\r", nbytes = 18446744073709551604, ...
which sounds highly like garbage. Well, the nbytes looks highly
like an unintentional negative number being wrapped into a positive
one by the virtue of the size_t in the prototype. In the caller
nbytes is 16. Digging more...
--
Jarkko Hietaniemi <jhi@iki.fi> http://www.iki.fi/jhi/ "There is this special
biologist word we use for 'stable'. It is 'dead'." -- Jack Cohen
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