[v1] hw/sd/sdcard: Verify CMD24 (Block Write) address is valid

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

Posted by Philippe Mathieu-Daudé 5 years, 8 months ago

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;
-- 
2.21.3

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

Posted by Paolo Bonzini 5 years, 8 months ago

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

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

Posted by Philippe Mathieu-Daudé 5 years, 8 months ago

On 6/4/20 8:03 PM, Paolo Bonzini wrote:
> 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.

Hmm I guess I typed "^RPrasad" in my shell to have the last git-publish
command with his email, and I didn't noticed you were also there...

Anyway looking at it again, this patch is wrong because I should check
for addr + blksize < sd_size instead. Can you drop it please?

>  Probably we should
> add qemu-block@nongnu.org to the hw/sd stanza.

OK will do.

> 
> Paolo
>