Re: [Qemu-devel] [PATCH] scsi: initialise info object with appropriate size

[Paolo Bonzini]

On 21/12/2015 10:43, P J P wrote:
>   Hello,
> 
> A stack overflow issue was reported by Mr Qinghao Tang, CC'd here. It
> occurs while processing the SCSI controller's CTRL_GET_INFO command, as
> the memset(2) call uses driver supplied 'cmd->iov_size' to initialise
> the '&info' object.
> 
> Please see below a proposed patch to fix this issue. Does it look okay?
> 
> ===
> From 5823b4a214ede884f4ba597fdd629862620e0f92 Mon Sep 17 00:00:00 2001
> From: Prasad J Pandit <address@hidden>
> Date: Mon, 21 Dec 2015 14:48:18 +0530
> Subject: [PATCH] scsi: initialise info object with appropriate size
> 
> While processing controller 'CTRL_GET_INFO' command, the routine
> 'megasas_ctrl_get_info' overflows the '&info' object size. Use its
> appropriate size to null initialise it.
> 
> Reported-by: Qinghao Tang <address@hidden>
> Signed-off-by: Prasad J Pandit <address@hidden>
> ---
>  hw/scsi/megasas.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/scsi/megasas.c b/hw/scsi/megasas.c
> index d7dc667..576f56c 100644
> --- a/hw/scsi/megasas.c
> +++ b/hw/scsi/megasas.c
> @@ -718,7 +718,7 @@ static int megasas_ctrl_get_info(MegasasState *s,
> MegasasCmd *cmd)
>      BusChild *kid;
>      int num_pd_disks = 0;
> 
> -    memset(&info, 0x0, cmd->iov_size);
> +    memset(&info, 0x0, dcmd_size);
>      if (cmd->iov_size < dcmd_size) {
>          trace_megasas_dcmd_invalid_xfer_len(cmd->index, cmd->iov_size,
>                                              dcmd_size);

Yes, it is.  I've queued this patch to my for-2.6 branch.

Paolo