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flann: fix out of buffer access

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This commit is contained in:
Alexander Alekhin 2017-07-26 18:16:39 +03:00
parent caa5e3b4c5
commit 12213f9985
1 changed files with 20 additions and 5 deletions
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25
modules/flann/include/opencv2/flann/lsh_table.h
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@ -147,6 +147,7 @@ public:
LshTable()
{
key_size_ = 0;
feature_size_ = 0;
speed_level_ = kArray;
}
@ -157,7 +158,7 @@ public:
*/
LshTable(unsigned int feature_size, unsigned int key_size)
{
(void)feature_size;
feature_size_ = feature_size;
(void)key_size;
std::cerr << "LSH is not implemented for that type" << std::endl;
assert(0);
@ -332,6 +333,8 @@ private:
*/
unsigned int key_size_;
unsigned int feature_size_;
// Members only used for the unsigned char specialization
/** The mask to apply to a feature to get the hash key
* Only used in the unsigned char case
@ -345,9 +348,10 @@ private:
template<>
inline LshTable<unsigned char>::LshTable(unsigned int feature_size, unsigned int subsignature_size)
{
feature_size_ = feature_size;
initialize(subsignature_size);
// Allocate the mask
mask_ = std::vector<size_t>((size_t)ceil((float)(feature_size * sizeof(char)) / (float)sizeof(size_t)), 0);
mask_ = std::vector<size_t>((feature_size * sizeof(char) + sizeof(size_t) - 1) / sizeof(size_t), 0);
// A bit brutal but fast to code
std::vector<size_t> indices(feature_size * CHAR_BIT);
@ -392,6 +396,7 @@ inline size_t LshTable<unsigned char>::getKey(const unsigned char* feature) cons
{
// no need to check if T is dividable by sizeof(size_t) like in the Hamming
// distance computation as we have a mask
// FIXIT: This is bad assumption, because we reading tail bytes after of the allocated features buffer
const size_t* feature_block_ptr = reinterpret_cast<const size_t*> ((const void*)feature);
// Figure out the subsignature of the feature
@ -400,10 +405,20 @@ inline size_t LshTable<unsigned char>::getKey(const unsigned char* feature) cons
size_t subsignature = 0;
size_t bit_index = 1;
for (std::vector<size_t>::const_iterator pmask_block = mask_.begin(); pmask_block != mask_.end(); ++pmask_block) {
for (unsigned i = 0; i < feature_size_; i += sizeof(size_t)) {
// get the mask and signature blocks
size_t feature_block = *feature_block_ptr;
size_t mask_block = *pmask_block;
size_t feature_block;
if (i <= feature_size_ - sizeof(size_t))
{
feature_block = *feature_block_ptr;
}
else
{
size_t tmp = 0;
memcpy(&tmp, feature_block_ptr, feature_size_ - i); // preserve bytes order
feature_block = tmp;
}
size_t mask_block = mask_[i / sizeof(size_t)];
while (mask_block) {
// Get the lowest set bit in the mask block
size_t lowest_bit = mask_block & (-(ptrdiff_t)mask_block);