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[Qemu-devel] [PATCH] fdc: force the fifo access to be in bounds of the a
From: |
John Snow |
Subject: |
[Qemu-devel] [PATCH] fdc: force the fifo access to be in bounds of the allocated buffer |
Date: |
Wed, 13 May 2015 10:33:21 -0400 |
From: Petr Matousek <address@hidden>
During processing of certain commands such as FD_CMD_READ_ID and
FD_CMD_DRIVE_SPECIFICATION_COMMAND the fifo memory access could
get out of bounds leading to memory corruption with values coming
from the guest.
Fix this by making sure that the index is always bounded by the
allocated memory.
This is CVE-2015-3456.
Signed-off-by: Petr Matousek <address@hidden>
Reviewed-by: John Snow <address@hidden>
Signed-off-by: John Snow <address@hidden>
---
hw/block/fdc.c | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)
diff --git a/hw/block/fdc.c b/hw/block/fdc.c
index f72a392..d8a8edd 100644
--- a/hw/block/fdc.c
+++ b/hw/block/fdc.c
@@ -1497,7 +1497,7 @@ static uint32_t fdctrl_read_data(FDCtrl *fdctrl)
{
FDrive *cur_drv;
uint32_t retval = 0;
- int pos;
+ uint32_t pos;
cur_drv = get_cur_drv(fdctrl);
fdctrl->dsr &= ~FD_DSR_PWRDOWN;
@@ -1506,8 +1506,8 @@ static uint32_t fdctrl_read_data(FDCtrl *fdctrl)
return 0;
}
pos = fdctrl->data_pos;
+ pos %= FD_SECTOR_LEN;
if (fdctrl->msr & FD_MSR_NONDMA) {
- pos %= FD_SECTOR_LEN;
if (pos == 0) {
if (fdctrl->data_pos != 0)
if (!fdctrl_seek_to_next_sect(fdctrl, cur_drv)) {
@@ -1852,10 +1852,13 @@ static void fdctrl_handle_option(FDCtrl *fdctrl, int
direction)
static void fdctrl_handle_drive_specification_command(FDCtrl *fdctrl, int
direction)
{
FDrive *cur_drv = get_cur_drv(fdctrl);
+ uint32_t pos;
- if (fdctrl->fifo[fdctrl->data_pos - 1] & 0x80) {
+ pos = fdctrl->data_pos - 1;
+ pos %= FD_SECTOR_LEN;
+ if (fdctrl->fifo[pos] & 0x80) {
/* Command parameters done */
- if (fdctrl->fifo[fdctrl->data_pos - 1] & 0x40) {
+ if (fdctrl->fifo[pos] & 0x40) {
fdctrl->fifo[0] = fdctrl->fifo[1];
fdctrl->fifo[2] = 0;
fdctrl->fifo[3] = 0;
@@ -1955,7 +1958,7 @@ static uint8_t command_to_handler[256];
static void fdctrl_write_data(FDCtrl *fdctrl, uint32_t value)
{
FDrive *cur_drv;
- int pos;
+ uint32_t pos;
/* Reset mode */
if (!(fdctrl->dor & FD_DOR_nRESET)) {
@@ -2004,7 +2007,9 @@ static void fdctrl_write_data(FDCtrl *fdctrl, uint32_t
value)
}
FLOPPY_DPRINTF("%s: %02x\n", __func__, value);
- fdctrl->fifo[fdctrl->data_pos++] = value;
+ pos = fdctrl->data_pos++;
+ pos %= FD_SECTOR_LEN;
+ fdctrl->fifo[pos] = value;
if (fdctrl->data_pos == fdctrl->data_len) {
/* We now have all parameters
* and will be able to treat the command
--
2.1.0
- [Qemu-devel] [PATCH] fdc: force the fifo access to be in bounds of the allocated buffer,
John Snow <=
- [Qemu-devel] [PATCH] fdc: force the fifo access to be in bounds of the allocated buffer, John Snow, 2015/05/13
- Re: [Qemu-devel] [PATCH] fdc: force the fifo access to be in bounds of the allocated buffer, Stefan Weil, 2015/05/13
- Re: [Qemu-devel] [Qemu-stable] [PATCH] fdc: force the fifo access to be in bounds of the allocated buffer, Stefan Priebe, 2015/05/13
- Re: [Qemu-devel] [Qemu-stable] [PATCH] fdc: force the fifo access to be in bounds of the allocated buffer, Stefan Weil, 2015/05/13
- Re: [Qemu-devel] [Qemu-stable] [PATCH] fdc: force the fifo access to be in bounds of the allocated buffer, Stefan Priebe, 2015/05/13
- Re: [Qemu-devel] [Qemu-stable] [PATCH] fdc: force the fifo access to be in bounds of the allocated buffer, Peter Lieven, 2015/05/13
- Re: [Qemu-devel] [Qemu-stable] [PATCH] fdc: force the fifo access to be in bounds of the allocated buffer, Markus Armbruster, 2015/05/13