2.4.22: do_brk with grsecurity also vulnerable?

Discuss usability issues, general maintenance, and general support issues for a grsecurity-enabled system.

2.4.22: do_brk with grsecurity also vulnerable?

Postby msi » Tue Dec 02, 2003 4:33 pm

hello, i'm using linux 2.4.22 with grseucirty and today i heard of the do_brk root-exploit. now my question: is my system also endangered?
what can I do to secure my system (except a kernel upgrade)?
msi
 
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Postby derRichard » Tue Dec 02, 2003 5:45 pm

derRichard
 
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Postby msw » Tue Dec 02, 2003 5:45 pm

Yes.

I have read that the exploit was successfully tested on linux 2.4.22 with grsecurity.
I'll upgrade to 2.4.23
msw
 
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Postby axehind » Tue Dec 02, 2003 6:11 pm

Anyone know when grsec2 for 2.4.23 is coming out? Brad?

axehind
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Postby Sleight of Mind » Tue Dec 02, 2003 6:21 pm

you could use http://www.grsecurity.net/~spender/grse ... -rc2.patch

but i would suggest using the cvs instead. It's 2.4.23 now and always has the latest fixes etc.
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Postby msi » Wed Dec 03, 2003 4:05 pm

hello everyone,

is this patch enough to block the do_brk hole:

Code: Select all
--- t/linux-2.4.21/mm/mmap.c    Fri Jun 13 16:51:39 2003
+++ linux-2.4.23/mm/mmap.c      Fri Nov 28 19:26:21 2003
@@ -1040,6 +1040,9 @@
        len = PAGE_ALIGN(len);
        if (!len)
                return addr;
+
+       if ((addr + len) > TASK_SIZE || (addr + len) < addr)
+               return -EINVAL;

        /*
         * mlock MCL_FUTURE?
msi
 
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Postby msi » Wed Dec 03, 2003 4:54 pm

hi,
my new kernel is up and running.
now, how can i test, wether my patch works? does anybody now, where i can get a exploit, or a program which tests the vulnerability?
msi
 
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Postby niz » Wed Dec 03, 2003 7:13 pm

There is some test program at bugtraq...
http://www.securityfocus.com/archive/1/ ... 03-12-06/0

I have not tested it..
niz
 
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Postby PaX Team » Wed Dec 03, 2003 7:17 pm

msi wrote:now, how can i test, wether my patch works? does anybody now, where i can get a exploit, or a program which tests the vulnerability?
http://archives.neohapsis.com/archives/bugtraq/2003-12/0011.html
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Postby msi » Thu Dec 04, 2003 2:03 pm

thx, my patch works.
msi
 
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