Re: [PATCH] hw/sd/sdcard: Verify CMD24 (Block Write) address is valid

[Paolo Bonzini]

On 04/06/20 19:34, Philippe Mathieu-Daudé wrote:
> Avoid OOB access by verifying the requested address belong to
> the actual card size. Return ADDRESS_ERROR when not in range.
> 
>   "SD Specifications Part 1 Physical Layer Simplified Spec. v3.01"
> 
>   4.3.4 Data Write
> 
>   * Block Write
> 
>   Write command is rejected if BLOCK_LEN_ERROR or ADDRESS_ERROR
>   occurred and no data transfer is performed.
> 
> Fixes: CVE-2020-13253
> Reported-by: Alexander Bulekov <alxndr@bu.edu>
> Buglink: https://bugs.launchpad.net/qemu/+bug/1880822
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> ---
> Cc: Prasad J Pandit <pjp@fedoraproject.org>
> ---
>  hw/sd/sd.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/hw/sd/sd.c b/hw/sd/sd.c
> index 3c06a0ac6d..0ced3b5e14 100644
> --- a/hw/sd/sd.c
> +++ b/hw/sd/sd.c
> @@ -1211,6 +1211,10 @@ static sd_rsp_type_t sd_normal_command(SDState *sd, 
> SDRequest req)
>              /* Writing in SPI mode not implemented.  */
>              if (sd->spi)
>                  break;
> +            if (addr >= sd->size) {
> +                sd->card_status |= ADDRESS_ERROR;
> +                return sd_r1;
> +            }
>              sd->state = sd_receivingdata_state;
>              sd->data_start = addr;
>              sd->data_offset = 0;
> 

I'm not sure if you want me to queue it, but I did.  Probably we should
add qemu-block@nongnu.org to the hw/sd stanza.

Paolo