full-disclosure - Second critical mremap() bug found in all Linux kernels

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Message-ID: <4034048A.50407@lorch.cc>
From: ml-daniel at lorch.cc (Daniel Lorch)
Subject: Second critical mremap() bug found in all Linux
 kernels

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hi

I checked LKML and Marcelo seems to recommend upgrading to 2.4.25.
This is currently not an option for me, as grsecurity-1.9.13-
2.4.24.patch won't properly apply against it. A friend (thanks,
Eike Frost) then pointed me to the following URL (bkbits reposi-
tory):

http://linux.bkbits.net:8080/linux-2.4/diffs/mm/mremap.c@...?nav=index.html|ChangeSet@...|cset@...323

After applying this patch the PoC provided by Christophe Devine
reports "kernel my not be vulnerable". This seems to have resolved
the issue. Hope this helps others, too.

$ uname -a
Linux tsunami4 2.4.24-grsec #3 Thu Feb 19 01:00:39 CET 2004 i686 unknown

$ ./a.out
mmap: Cannot allocate memory
created ~65531 VMAs
now mremapping 0x3FFE9000 at 0x3FFE5000
kernel may not be vulnerable

daniel

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