72 lines
		
	
	
		
			2.7 KiB
		
	
	
	
		
			Diff
		
	
	
	
	
	
			
		
		
	
	
			72 lines
		
	
	
		
			2.7 KiB
		
	
	
	
		
			Diff
		
	
	
	
	
	
| From 58ee0fd916671942e62ac9930f18225761a6dd66 Mon Sep 17 00:00:00 2001
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| From: Joe Richey <joerichey@google.com>
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| Date: Tue, 21 Jan 2020 20:04:45 -0800
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| Subject: [PATCH] mu: Remove use of VLAs for Marshalling TPML types
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| 
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| All of the `Tss2_MU_*_Marshal()` functions have the property that
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| `buffer` can be NULL, `offset` can be NULL, but both cannot be
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| NULL. Some Marshal functions check this directly (returning
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| `TSS2_MU_RC_BAD_REFERENCE` on error), but most do this by composing
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| existing Marshalling functions together.
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| 
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| The TMPL Marshal functions does things differently, it creates a local
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| VLA `local_buffer[buffer_size]` and uses that as the buffer pointer if
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| a NULL buffer is given. This is unnecessary, as this pointer is only
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| used for debug logging and passed to other Marshalling functions, which
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| will correctly handle a NULL buffer.
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| 
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| Note that the VLA in the existing code is of length `buffer_size` (the
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| length of the _entire_ buffer, _not_ the length of the data being
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| unmarshaled). This can potentially result in a very large stack
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| allocation, or stack overflow.
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| 
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| Signed-off-by: Joe Richey <joerichey@google.com>
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| ---
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|  src/tss2-mu/tpml-types.c | 11 +++--------
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|  1 file changed, 3 insertions(+), 8 deletions(-)
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| 
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| diff --git a/src/tss2-mu/tpml-types.c b/src/tss2-mu/tpml-types.c
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| index 9506a26efd14..ae1ed6177d75 100644
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| --- a/src/tss2-mu/tpml-types.c
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| +++ b/src/tss2-mu/tpml-types.c
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| @@ -29,8 +29,6 @@ TSS2_RC Tss2_MU_##type##_Marshal(type const *src, uint8_t buffer[], \
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|      size_t  local_offset = 0; \
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|      UINT32 i, count = 0; \
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|      TSS2_RC ret = TSS2_RC_SUCCESS; \
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| -    uint8_t *buf_ptr = buffer; \
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| -    uint8_t local_buffer[buffer_size]; \
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|  \
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|      if (offset != NULL) { \
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|          LOG_TRACE("offset non-NULL, initial value: %zu", *offset); \
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| @@ -60,24 +58,21 @@ TSS2_RC Tss2_MU_##type##_Marshal(type const *src, uint8_t buffer[], \
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|          LOG_WARNING("count too big"); \
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|          return TSS2_SYS_RC_BAD_VALUE; \
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|      } \
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| -\
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| -    if (buf_ptr == NULL) \
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| -        buf_ptr = local_buffer; \
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|  \
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|      LOG_DEBUG(\
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|           "Marshalling " #type " from 0x%" PRIxPTR " to buffer 0x%" PRIxPTR \
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|           " at index 0x%zx", \
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|           (uintptr_t)&src, \
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| -         (uintptr_t)buf_ptr, \
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| +         (uintptr_t)buffer, \
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|           local_offset); \
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|  \
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| -    ret = Tss2_MU_UINT32_Marshal(src->count, buf_ptr, buffer_size, &local_offset); \
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| +    ret = Tss2_MU_UINT32_Marshal(src->count, buffer, buffer_size, &local_offset); \
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|      if (ret) \
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|          return ret; \
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|  \
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|      for (i = 0; i < src->count; i++) \
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|      { \
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| -        ret = marshal_func(op src->buf_name[i], buf_ptr, buffer_size, &local_offset); \
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| +        ret = marshal_func(op src->buf_name[i], buffer, buffer_size, &local_offset); \
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|          if (ret) \
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|              return ret; \
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|      } \
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| -- 
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| 2.27.0
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| 
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