File 0040-fdc-force-the-fifo-access-to-be-in-.patch of Package qemu-linux-user

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File 0040-fdc-force-the-fifo-access-to-be-in-.patch of Package qemu-linux-user

From 7c08e75ea8b769461c32697e28bf8b66e878b1ef Mon Sep 17 00:00:00 2001
From: Petr Matousek <pmatouse@redhat.com>
Date: Wed, 6 May 2015 09:48:59 +0200
Subject: [PATCH] fdc: force the fifo access to be in bounds of the allocated
 buffer
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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 <pmatouse@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
(cherry picked from commit e907746266721f305d67bc0718795fedee2e824c)
[AF: BOO#929339]
Signed-off-by: Andreas Färber <afaerber@suse.de>
---
 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 490d127..045459e 100644
--- a/hw/block/fdc.c
+++ b/hw/block/fdc.c
@@ -1436,7 +1436,7 @@ 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;
@@ -1445,8 +1445,8 @@ 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)) {
@@ -1790,10 +1790,13 @@ 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;
@@ -1893,7 +1896,7 @@ 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)) {
@@ -1941,7 +1944,9 @@ 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

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File 0040-fdc-force-the-fifo-access-to-be-in-.patch of Package qemu-linux-user

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