[Qemu-devel] [4293] FDC: Fix buffer overflow (Herv?\195?\169 Poussineau)

[Blue Swirl]

Revision: 4293
          http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=4293
Author:   blueswir1
Date:     2008-05-01 19:03:31 +0000 (Thu, 01 May 2008)

Log Message:
-----------
FDC: Fix buffer overflow (Herv?\195?\169 Poussineau)

In floppy controller, programming PIO writes which are more than one sector
long leads to a buffer overflow of the fdtrl->fifo[] array.

Modified Paths:
--------------
    trunk/hw/fdc.c

Modified: trunk/hw/fdc.c
===================================================================
--- trunk/hw/fdc.c      2008-05-01 18:21:46 UTC (rev 4292)
+++ trunk/hw/fdc.c      2008-05-01 19:03:31 UTC (rev 4293)
@@ -1770,8 +1770,10 @@
     /* Is it write command time ? */
     if (fdctrl->msr & FD_MSR_NONDMA) {
         /* FIFO data write */
-        fdctrl->fifo[fdctrl->data_pos++] = value;
-        if (fdctrl->data_pos % FD_SECTOR_LEN == (FD_SECTOR_LEN - 1) ||
+        pos = fdctrl->data_pos++;
+        pos %= FD_SECTOR_LEN;
+        fdctrl->fifo[pos] = value;
+        if (pos == FD_SECTOR_LEN - 1 ||
             fdctrl->data_pos == fdctrl->data_len) {
             cur_drv = get_cur_drv(fdctrl);
             if (bdrv_write(cur_drv->bs, fd_sector(cur_drv), fdctrl->fifo, 1) < 
0) {