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From: Alexander Graf <agraf@suse.de>
Message-ID: <5745873C.90400@suse.de>
Date: Wed, 25 May 2016 13:06:36 +0200
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Subject: Re: [Qemu-devel] [PATCH 1/3] scsi: megasas: use appropriate
 property buffer size
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To: P J P <ppandit@redhat.com>, Qemu Developers <qemu-devel@nongnu.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>, Li Qiang <liqiang6-s@360.cn>, Hannes Reinecke <hare@suse.de>, Prasad J Pandit <pjp@fedoraproject.org>

On 05/25/2016 12:31 PM, P J P wrote:
> From: Prasad J Pandit <pjp@fedoraproject.org>
>
> When setting MegaRAID SAS controller properties via MegaRAID
> Firmware Interface(MFI) commands, a user supplied size parameter
> is used to set property value. Use appropriate size value to avoid
> OOB access issues.
>
> Reported-by: Li Qiang <liqiang6-s@360.cn>
> Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
> ---
>   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 a63a581..dcbd3e1 100644
> --- a/hw/scsi/megasas.c
> +++ b/hw/scsi/megasas.c
> @@ -1446,7 +1446,7 @@ static int megasas_dcmd_set_properties(MegasasState *s, MegasasCmd *cmd)
>                                               dcmd_size);
>           return MFI_STAT_INVALID_PARAMETER;
>       }
> -    dma_buf_write((uint8_t *)&info, cmd->iov_size, &cmd->qsg);
> +    dma_buf_write((uint8_t *)&info, dcmd_size, &cmd->qsg);

This looks odd - can dcmd_size be bigger than iov_size? Wouldn't we 
overwrite guest memory then? And where does dcmd_size come from? I don't 
see it in master.


Alex

>       trace_megasas_dcmd_unsupported(cmd->index, cmd->iov_size);
>       return MFI_STAT_OK;
>   }