From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48029) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZKm71-00059I-QJ for qemu-devel@nongnu.org; Thu, 30 Jul 2015 07:35:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZKm6y-0001fn-50 for qemu-devel@nongnu.org; Thu, 30 Jul 2015 07:34:59 -0400 Received: from e32.co.us.ibm.com ([32.97.110.150]:49768) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZKm6x-0001fO-VT for qemu-devel@nongnu.org; Thu, 30 Jul 2015 07:34:56 -0400 Received: from /spool/local by e32.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 30 Jul 2015 05:34:55 -0600 From: Michael Roth Date: Thu, 30 Jul 2015 06:32:26 -0500 Message-Id: <1438255988-10418-12-git-send-email-mdroth@linux.vnet.ibm.com> In-Reply-To: <1438255988-10418-1-git-send-email-mdroth@linux.vnet.ibm.com> References: <1438255988-10418-1-git-send-email-mdroth@linux.vnet.ibm.com> Subject: [Qemu-devel] [PATCH 11/53] fdc: force the fifo access to be in bounds of the allocated buffer List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: John Snow , Petr Matousek , qemu-stable@nongnu.org From: Petr Matousek 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 Reviewed-by: John Snow Signed-off-by: John Snow (cherry picked from commit e907746266721f305d67bc0718795fedee2e824c) Signed-off-by: Michael Roth --- 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 2bf87c9..a9de4ab 100644 --- a/hw/block/fdc.c +++ b/hw/block/fdc.c @@ -1512,7 +1512,7 @@ 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; @@ -1521,8 +1521,8 @@ 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)) { @@ -1867,10 +1867,13 @@ 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; @@ -1970,7 +1973,7 @@ 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)) { @@ -2019,7 +2022,9 @@ 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 -- 1.9.1