debian/patches/0001-fdc-force-the-fifo-access-to-be-in-bounds-of-the-all.patch

   1 From 8cb8ea32396f52e01cdb38c00b5b7f5a0141f97f Mon Sep 17 00:00:00 2001
   2 From: Petr Matousek <pmatouse@redhat.com>
   3 Date: Wed, 6 May 2015 09:48:59 +0200
   4 Subject: [PATCH] fdc: force the fifo access to be in bounds of the allocated
   5  buffer
   6
   7 During processing of certain commands such as FD_CMD_READ_ID and
   8 FD_CMD_DRIVE_SPECIFICATION_COMMAND the fifo memory access could
   9 get out of bounds leading to memory corruption with values coming
  10 from the guest.
  11
  12 Fix this by making sure that the index is always bounded by the
  13 allocated memory.
  14
  15 This is CVE-2015-3456.
  16
  17 Signed-off-by: Petr Matousek <pmatouse@redhat.com>
  18 Reviewed-by: John Snow <jsnow@redhat.com>
  19 Signed-off-by: John Snow <jsnow@redhat.com>
  20 (cherry picked from commit e907746266721f305d67bc0718795fedee2e824c)
  21 Signed-off-by: Stefan Priebe <s.priebe@profihost.ag>
  22 ---
  23  hw/block/fdc.c |   17 +++++++++++------
  24  1 file changed, 11 insertions(+), 6 deletions(-)
  25
  26 diff --git a/hw/block/fdc.c b/hw/block/fdc.c
  27 index 739a03e..1168e8c 100644
  28 --- a/hw/block/fdc.c
  29 +++ b/hw/block/fdc.c
  30 @@ -1512,7 +1512,7 @@ static uint32_t fdctrl_read_data(FDCtrl *fdctrl)
  31  {
  32      FDrive *cur_drv;
  33      uint32_t retval = 0;
  34 -    int pos;
  35 +    uint32_t pos;
  36
  37      cur_drv = get_cur_drv(fdctrl);
  38      fdctrl->dsr &= ~FD_DSR_PWRDOWN;
  39 @@ -1521,8 +1521,8 @@ static uint32_t fdctrl_read_data(FDCtrl *fdctrl)
  40          return 0;
  41      }
  42      pos = fdctrl->data_pos;
  43 +    pos %= FD_SECTOR_LEN;
  44      if (fdctrl->msr & FD_MSR_NONDMA) {
  45 -        pos %= FD_SECTOR_LEN;
  46          if (pos == 0) {
  47              if (fdctrl->data_pos != 0)
  48                  if (!fdctrl_seek_to_next_sect(fdctrl, cur_drv)) {
  49 @@ -1867,10 +1867,13 @@ static void fdctrl_handle_option(FDCtrl *fdctrl, int direction)
  50  static void fdctrl_handle_drive_specification_command(FDCtrl *fdctrl, int direction)
  51  {
  52      FDrive *cur_drv = get_cur_drv(fdctrl);
  53 +    uint32_t pos;
  54
  55 -    if (fdctrl->fifo[fdctrl->data_pos - 1] & 0x80) {
  56 +    pos = fdctrl->data_pos - 1;
  57 +    pos %= FD_SECTOR_LEN;
  58 +    if (fdctrl->fifo[pos] & 0x80) {
  59          /* Command parameters done */
  60 -        if (fdctrl->fifo[fdctrl->data_pos - 1] & 0x40) {
  61 +        if (fdctrl->fifo[pos] & 0x40) {
  62              fdctrl->fifo[0] = fdctrl->fifo[1];
  63              fdctrl->fifo[2] = 0;
  64              fdctrl->fifo[3] = 0;
  65 @@ -1970,7 +1973,7 @@ static uint8_t command_to_handler[256];
  66  static void fdctrl_write_data(FDCtrl *fdctrl, uint32_t value)
  67  {
  68      FDrive *cur_drv;
  69 -    int pos;
  70 +    uint32_t pos;
  71
  72      /* Reset mode */
  73      if (!(fdctrl->dor & FD_DOR_nRESET)) {
  74 @@ -2019,7 +2022,9 @@ static void fdctrl_write_data(FDCtrl *fdctrl, uint32_t value)
  75      }
  76
  77      FLOPPY_DPRINTF("%s: %02x\n", __func__, value);
  78 -    fdctrl->fifo[fdctrl->data_pos++] = value;
  79 +    pos = fdctrl->data_pos++;
  80 +    pos %= FD_SECTOR_LEN;
  81 +    fdctrl->fifo[pos] = value;
  82      if (fdctrl->data_pos == fdctrl->data_len) {
  83          /* We now have all parameters
  84           * and will be able to treat the command
  85 --
  86 1.7.10.4
  87