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[PATCH v1] sd: sdhci: assert data_count is within fifo_buffer

P J P posted 1 patch 5 years, 2 months ago
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git fetch https://github.com/patchew-project/qemu tags/patchew/20200903070842.2125083-1-ppandit@redhat.com
hw/sd/sdhci.c | 2 ++
1 file changed, 2 insertions(+)
[PATCH v1] sd: sdhci: assert data_count is within fifo_buffer
Posted by P J P 5 years, 2 months ago 
From: Prasad J Pandit <pjp@fedoraproject.org>

While doing multi block SDMA, transfer block size may exceed
the 's->fifo_buffer[s->buf_maxsz]' size. It may leave the
current element pointer 's->data_count' pointing out of bounds.
Leading the subsequent DMA r/w operation to OOB access issue.
Assert that 's->data_count' is within fifo_buffer.

 -> https://ruhr-uni-bochum.sciebo.de/s/NNWP2GfwzYKeKwE?path=%2Fsdhci_oob_write1
 ==1459837==ERROR: AddressSanitizer: heap-buffer-overflow
 WRITE of size 54722048 at 0x61500001e280 thread T3
 #0  __interceptor_memcpy (/lib64/libasan.so.6+0x3a71d)
 #1  flatview_read_continue ../exec.c:3245
 #2  flatview_read ../exec.c:3278
 #3  address_space_read_full ../exec.c:3291
 #4  address_space_rw ../exec.c:3319
 #5  dma_memory_rw_relaxed ../include/sysemu/dma.h:87
 #6  dma_memory_rw ../include/sysemu/dma.h:110
 #7  dma_memory_read ../include/sysemu/dma.h:116
 #8  sdhci_sdma_transfer_multi_blocks ../hw/sd/sdhci.c:629
 #9  sdhci_write ../hw/sd/sdhci.c:1097
 #10 memory_region_write_accessor ../softmmu/memory.c:483
 ...

Reported-by: Ruhr-University <bugs-syssec@rub.de>
Suggested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
---
 hw/sd/sdhci.c | 2 ++
 1 file changed, 2 insertions(+)

Update v1: use assert(3) calls
  -> https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg00966.html

diff --git a/hw/sd/sdhci.c b/hw/sd/sdhci.c
index 1785d7e1f7..023acbed41 100644
--- a/hw/sd/sdhci.c
+++ b/hw/sd/sdhci.c
@@ -604,6 +604,7 @@ static void sdhci_sdma_transfer_multi_blocks(SDHCIState *s)
                     s->blkcnt--;
                 }
             }
+            assert(s->data_count <= s->buf_maxsz && s->data_count > begin);
             dma_memory_write(s->dma_as, s->sdmasysad,
                              &s->fifo_buffer[begin], s->data_count - begin);
             s->sdmasysad += s->data_count - begin;
@@ -626,6 +627,7 @@ static void sdhci_sdma_transfer_multi_blocks(SDHCIState *s)
                 s->data_count = block_size;
                 boundary_count -= block_size - begin;
             }
+            assert(s->data_count <= s->buf_maxsz && s->data_count > begin);
             dma_memory_read(s->dma_as, s->sdmasysad,
                             &s->fifo_buffer[begin], s->data_count - begin);
             s->sdmasysad += s->data_count - begin;
-- 
2.26.2
Re: [PATCH v1] sd: sdhci: assert data_count is within fifo_buffer
Posted by Philippe Mathieu-Daudé 5 years, 2 months ago 
On 9/3/20 9:08 AM, P J P wrote:
> From: Prasad J Pandit <pjp@fedoraproject.org>
> 
> While doing multi block SDMA, transfer block size may exceed
> the 's->fifo_buffer[s->buf_maxsz]' size. It may leave the
> current element pointer 's->data_count' pointing out of bounds.
> Leading the subsequent DMA r/w operation to OOB access issue.
> Assert that 's->data_count' is within fifo_buffer.
> 
>  -> https://ruhr-uni-bochum.sciebo.de/s/NNWP2GfwzYKeKwE?path=%2Fsdhci_oob_write1
>  ==1459837==ERROR: AddressSanitizer: heap-buffer-overflow
>  WRITE of size 54722048 at 0x61500001e280 thread T3
>  #0  __interceptor_memcpy (/lib64/libasan.so.6+0x3a71d)
>  #1  flatview_read_continue ../exec.c:3245
>  #2  flatview_read ../exec.c:3278
>  #3  address_space_read_full ../exec.c:3291
>  #4  address_space_rw ../exec.c:3319
>  #5  dma_memory_rw_relaxed ../include/sysemu/dma.h:87
>  #6  dma_memory_rw ../include/sysemu/dma.h:110
>  #7  dma_memory_read ../include/sysemu/dma.h:116
>  #8  sdhci_sdma_transfer_multi_blocks ../hw/sd/sdhci.c:629
>  #9  sdhci_write ../hw/sd/sdhci.c:1097
>  #10 memory_region_write_accessor ../softmmu/memory.c:483
>  ...
> 
> Reported-by: Ruhr-University <bugs-syssec@rub.de>
> Suggested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
> ---
>  hw/sd/sdhci.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> Update v1: use assert(3) calls
>   -> https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg00966.html
> 
> diff --git a/hw/sd/sdhci.c b/hw/sd/sdhci.c
> index 1785d7e1f7..023acbed41 100644
> --- a/hw/sd/sdhci.c
> +++ b/hw/sd/sdhci.c
> @@ -604,6 +604,7 @@ static void sdhci_sdma_transfer_multi_blocks(SDHCIState *s)
>                      s->blkcnt--;
>                  }
>              }
> +            assert(s->data_count <= s->buf_maxsz && s->data_count > begin);
>              dma_memory_write(s->dma_as, s->sdmasysad,
>                               &s->fifo_buffer[begin], s->data_count - begin);
>              s->sdmasysad += s->data_count - begin;
> @@ -626,6 +627,7 @@ static void sdhci_sdma_transfer_multi_blocks(SDHCIState *s)
>                  s->data_count = block_size;
>                  boundary_count -= block_size - begin;
>              }
> +            assert(s->data_count <= s->buf_maxsz && s->data_count > begin);
>              dma_memory_read(s->dma_as, s->sdmasysad,
>                              &s->fifo_buffer[begin], s->data_count - begin);
>              s->sdmasysad += s->data_count - begin;
> 

qemu-system-i386: hw/sd/sdhci.c:632: void
sdhci_sdma_transfer_multi_blocks(SDHCIState *): Assertion `s->data_count
<= s->buf_maxsz && s->data_count > begin' failed.

Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

If you don't mind I might split the assert in 2 when applying:

-            assert(s->data_count <= s->buf_maxsz && s->data_count > begin);
+            assert(s->data_count <= s->buf_maxsz);
+            assert(s->data_count > begin);

To directly display the problem straight:

qemu-system-i386: hw/sd/sdhci.c:635: void
sdhci_sdma_transfer_multi_blocks(SDHCIState *): Assertion `s->data_count
> begin' failed.

Thanks,

Phil.
Re: [PATCH v1] sd: sdhci: assert data_count is within fifo_buffer
Posted by Philippe Mathieu-Daudé 5 years, 2 months ago 
On 9/3/20 4:01 PM, Philippe Mathieu-Daudé wrote:
> On 9/3/20 9:08 AM, P J P wrote:
>> From: Prasad J Pandit <pjp@fedoraproject.org>
>>
>> While doing multi block SDMA, transfer block size may exceed
>> the 's->fifo_buffer[s->buf_maxsz]' size. It may leave the
>> current element pointer 's->data_count' pointing out of bounds.
>> Leading the subsequent DMA r/w operation to OOB access issue.
>> Assert that 's->data_count' is within fifo_buffer.
>>
>>  -> https://ruhr-uni-bochum.sciebo.de/s/NNWP2GfwzYKeKwE?path=%2Fsdhci_oob_write1
>>  ==1459837==ERROR: AddressSanitizer: heap-buffer-overflow
>>  WRITE of size 54722048 at 0x61500001e280 thread T3
>>  #0  __interceptor_memcpy (/lib64/libasan.so.6+0x3a71d)
>>  #1  flatview_read_continue ../exec.c:3245
>>  #2  flatview_read ../exec.c:3278
>>  #3  address_space_read_full ../exec.c:3291
>>  #4  address_space_rw ../exec.c:3319
>>  #5  dma_memory_rw_relaxed ../include/sysemu/dma.h:87
>>  #6  dma_memory_rw ../include/sysemu/dma.h:110
>>  #7  dma_memory_read ../include/sysemu/dma.h:116
>>  #8  sdhci_sdma_transfer_multi_blocks ../hw/sd/sdhci.c:629
>>  #9  sdhci_write ../hw/sd/sdhci.c:1097
>>  #10 memory_region_write_accessor ../softmmu/memory.c:483
>>  ...
>>
>> Reported-by: Ruhr-University <bugs-syssec@rub.de>
>> Suggested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
>> Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
>> ---
>>  hw/sd/sdhci.c | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> Update v1: use assert(3) calls
>>   -> https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg00966.html
>>
>> diff --git a/hw/sd/sdhci.c b/hw/sd/sdhci.c
>> index 1785d7e1f7..023acbed41 100644
>> --- a/hw/sd/sdhci.c
>> +++ b/hw/sd/sdhci.c
>> @@ -604,6 +604,7 @@ static void sdhci_sdma_transfer_multi_blocks(SDHCIState *s)
>>                      s->blkcnt--;
>>                  }
>>              }
>> +            assert(s->data_count <= s->buf_maxsz && s->data_count > begin);
>>              dma_memory_write(s->dma_as, s->sdmasysad,
>>                               &s->fifo_buffer[begin], s->data_count - begin);
>>              s->sdmasysad += s->data_count - begin;
>> @@ -626,6 +627,7 @@ static void sdhci_sdma_transfer_multi_blocks(SDHCIState *s)
>>                  s->data_count = block_size;
>>                  boundary_count -= block_size - begin;
>>              }
>> +            assert(s->data_count <= s->buf_maxsz && s->data_count > begin);
>>              dma_memory_read(s->dma_as, s->sdmasysad,
>>                              &s->fifo_buffer[begin], s->data_count - begin);
>>              s->sdmasysad += s->data_count - begin;
>>
> 
> qemu-system-i386: hw/sd/sdhci.c:632: void
> sdhci_sdma_transfer_multi_blocks(SDHCIState *): Assertion `s->data_count
> <= s->buf_maxsz && s->data_count > begin' failed.
> 
> Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> 
> If you don't mind I might split the assert in 2 when applying:
> 
> -            assert(s->data_count <= s->buf_maxsz && s->data_count > begin);
> +            assert(s->data_count <= s->buf_maxsz);
> +            assert(s->data_count > begin);

Doesn't seem enough, guest crash here, having:

(gdb) p begin
$1 = 0
(gdb) p s->data_count
$2 = 0
(gdb) p s->blksize
$3 = 0

Beh, something is wrong in this model, because when using ADMA2
length 0 means 65536 bytes (see '1.13.4. Descriptor Table' in
"SD Host Controller Simplified Specification Version 2.00").
Re: [PATCH v1] sd: sdhci: assert data_count is within fifo_buffer
Posted by P J P 5 years, 2 months ago 
+-- On Thu, 3 Sep 2020, Philippe Mathieu-Daudé wrote --+
| > -            assert(s->data_count <= s->buf_maxsz && s->data_count > begin);
| > +            assert(s->data_count <= s->buf_maxsz);
| > +            assert(s->data_count > begin);
| 
| Doesn't seem enough, guest crash here, having:
| 
| (gdb) p begin
| $1 = 0
| (gdb) p s->data_count
| $2 = 0

I was actually thinking of a case if 's->data_count' and 'begin' are same? It 
may lead to an infinite loop condition.

| (gdb) p s->blksize
| $3 = 0

This is strange. 

| Beh, something is wrong in this model, because when using ADMA2
| length 0 means 65536 bytes (see '1.13.4. Descriptor Table' in
| "SD Host Controller Simplified Specification Version 2.00").

* DMA length 's->data_count - begin'?

* if s->blksize is 65536, it'd set 'block_size = 0' in transfer_multi_blocks()

   #define BLOCK_SIZE_MASK (4 * KiB - 1)  <== 0xFFF

   static void sdhci_sdma_transfer_multi_blocks(SDHCIState *s)                     
   {
     ...
     const uint16_t block_size = s->blksize & BLOCK_SIZE_MASK;  <== 0


Thank you.
--
Prasad J Pandit / Red Hat Product Security Team
8685 545E B54C 486B C6EB 271E E285 8B5A F050 DE8D
Re: [PATCH v1] sd: sdhci: assert data_count is within fifo_buffer
Posted by P J P 5 years, 2 months ago 
+-- On Thu, 3 Sep 2020, Philippe Mathieu-Daudé wrote --+
| If you don't mind I might split the assert in 2 when applying:
| 
| -            assert(s->data_count <= s->buf_maxsz && s->data_count > begin);
| +            assert(s->data_count <= s->buf_maxsz);
| +            assert(s->data_count > begin);

Sure, np. Thank you.
--
Prasad J Pandit / Red Hat Product Security Team
8685 545E B54C 486B C6EB 271E E285 8B5A F050 DE8D

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