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Adding more checks to canonical Huffman decoder's table initialization function. They don't seem necessary, as I didn't discover them during fuzzing. These fixes are precautionary.

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This commit is contained in:
Rich Geldreich
2019-05-10 16:30:15 -07:00
parent 5a9c6e5b05
commit 4f08db6525
1 changed files with 22 additions and 3 deletions
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25
transcoder/basisu_transcoder_internal.h
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@@ -123,6 +123,12 @@ namespace basist
uint32_t k = (code_size << 16) | sym_index;
while (rev_code < basisu::cHuffmanFastLookupSize)
{
if (m_lookup[rev_code] != 0)
{
// Supplied codesizes can't create a valid prefix code.
return false;
}
m_lookup[rev_code] = k;
rev_code += (1 << code_size);
}
@@ -132,7 +138,14 @@ namespace basist
int tree_cur;
if (0 == (tree_cur = m_lookup[rev_code & (basisu::cHuffmanFastLookupSize - 1)]))
{
m_lookup[rev_code & (basisu::cHuffmanFastLookupSize - 1)] = tree_next;
const uint32_t idx = rev_code & (basisu::cHuffmanFastLookupSize - 1);
if (m_lookup[idx] != 0)
{
// Supplied codesizes can't create a valid prefix code.
return false;
}
m_lookup[idx] = tree_next;
tree_cur = tree_next;
tree_next -= 2;
}
@@ -149,7 +162,7 @@ namespace basist
{
tree_cur -= ((rev_code >>= 1) & 1);
int idx = -tree_cur - 1;
const int idx = -tree_cur - 1;
if (idx < 0)
return false;
else if (idx >= (int)m_tree.size())
@@ -174,12 +187,18 @@ namespace basist
tree_cur -= ((rev_code >>= 1) & 1);
int idx = -tree_cur - 1;
const int idx = -tree_cur - 1;
if (idx < 0)
return false;
else if (idx >= (int)m_tree.size())
m_tree.resize(idx + 1);
if (m_tree[idx] != 0)
{
// Supplied codesizes can't create a valid prefix code.
return false;
}
m_tree[idx] = (int16_t)sym_index;
}