MdeModulePkg BrotliDecompressLib: Add the checker to avoid array out of bound

This change is to pass static analysis.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Star Zeng <star.zeng@intel.com>

1 files changed, 8 insertions, 5 deletions

diff --git a/MdeModulePkg/Library/BrotliCustomDecompressLib/dec/decode.c b/MdeModulePkg/Library/BrotliCustomDecompressLib/dec/decode.c
index fd42b3b930..f3b3cb8971 100644
--- a/MdeModulePkg/Library/BrotliCustomDecompressLib/dec/decode.c
+++ b/MdeModulePkg/Library/BrotliCustomDecompressLib/dec/decode.c
@@ -858,6 +858,7 @@ static BROTLI_INLINE uint32_t ReadBlockLength(const HuffmanCode* table,
   uint32_t code;

   uint32_t nbits;

   code = ReadSymbol(table, br);

+  ASSERT (code < BROTLI_NUM_BLOCK_LEN_SYMBOLS);

   nbits = kBlockLengthPrefixCode[code].nbits;  /* nbits == 2..24 */

   return kBlockLengthPrefixCode[code].offset + BrotliReadBits(br, nbits);

 }

@@ -910,6 +911,7 @@ static BROTLI_NOINLINE void InverseMoveToFrontTransform(
   uint32_t upper_bound = state->mtf_upper_bound;

   uint32_t* mtf = &state->mtf[1];  /* Make mtf[-1] addressable. */

   uint8_t* mtf_u8 = (uint8_t*)mtf;

+  uint8_t* mtf_u8t = mtf_u8 - 1;

   /* Load endian-aware constant. */

   const uint8_t b0123[4] = {0, 1, 2, 3};

   uint32_t pattern;

@@ -928,13 +930,13 @@ static BROTLI_NOINLINE void InverseMoveToFrontTransform(
   for (i = 0; i < v_len; ++i) {

     int index = v[i];

     uint8_t value = mtf_u8[index];

-    upper_bound |= v[i];

+    upper_bound |= (uint32_t) v[i];

     v[i] = value;

-    mtf_u8[-1] = value;

-    do {

+    mtf_u8t[0] = value;

+    while (index >= 0) {

+      mtf_u8t[index + 1] = mtf_u8t[index];

       index--;

-      mtf_u8[index + 1] = mtf_u8[index];

-    } while (index >= 0);

+    }

   }

   /* Remember amount of elements to be reinitialized. */

   state->mtf_upper_bound = upper_bound >> 2;

@@ -1566,6 +1568,7 @@ static BROTLI_INLINE BROTLI_BOOL ReadCommandInternal(
   BrotliBitReaderState memento;

   if (!safe) {

     cmd_code = ReadSymbol(s->htree_command, br);

+    ASSERT (cmd_code < BROTLI_NUM_COMMAND_SYMBOLS);

   } else {

     BrotliBitReaderSaveState(br, &memento);

     if (!SafeReadSymbol(s->htree_command, br, &cmd_code)) {