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Bound header_length and check shape-product overflow when loading .npy (fix #44) #45

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Bound header_length and check shape-product overflow when loading .npy (fix #44) #45

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d05cd28
Bound header_length and check shape-product overflow when loading .npy
Jun 5, 2026
eef12f9
Add missing #include <limits> for std::numeric_limits (fixes CI build)
Jun 6, 2026
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18 changes: 17 additions & 1 deletion include/npy.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,7 @@
#include <fstream>
#include <iostream>
#include <iterator>
#include <limits>
#include <sstream>
#include <stdexcept>
#include <string>
Expand Down Expand Up @@ -445,6 +446,15 @@ inline std::string read_header(std::istream &istream) {
throw std::runtime_error("unsupported file format version");
}

// Bound the attacker-controlled header_length before allocating: a crafted .npy can
// declare header_length up to 4 GiB (v2 u32), forcing a huge allocation (DoS). The cap
// is generous (well above any real header, which is at most a few hundred KB even for
// large structured dtypes) so legitimate v1 and v2 files are unaffected; tune as needed.
static const uint32_t max_header_length = 16u * 1024u * 1024u;
if (header_length > max_header_length) {
throw std::runtime_error("invalid file format: header_length exceeds maximum");
}

auto buf_v = std::vector<char>(header_length);
istream.read(buf_v.data(), header_length);
std::string header(buf_v.data(), header_length);
Expand All @@ -454,7 +464,13 @@ inline std::string read_header(std::istream &istream) {

inline ndarray_len_t comp_size(const shape_t &shape) {
ndarray_len_t size = 1;
for (ndarray_len_t i : shape) size *= i;
for (ndarray_len_t i : shape) {
// Reject overflow of the shape product (CWE-190): a wrapped product yields a
// silent undersized buffer or a giant allocation downstream.
if (i != 0 && size > std::numeric_limits<ndarray_len_t>::max() / i)
throw std::runtime_error("invalid file format: shape product overflow");
size *= i;
}

return size;
}
Expand Down