CVE-2021-37686: Infinite loop in TensorFlow Lite

Impact The strided slice implementation in TFLite has a logic bug which can allow an attacker to trigger an infinite loop. This arises from newly introduced support for ellipsis in axis definition:

cc for (int i = 0; i < effectivedims;) { if ((1 << i) & opcontext->params->ellipsismask) { // ... int ellipsisendidx = std::min(i + 1 + numaddaxis + opcontext->inputdims - begincount, effectivedims); // ... for (; i < ellipsisendidx; ++i) { // ... } continue; } // ... ++i; }

An attacker can craft a model such that ellipsisendidx is smaller than i (e.g., always negative). In this case, the inner loop does not increase i and the continue statement causes execution to skip over the preincrement at the end of the outer loop.

Patches We have patched the issue in GitHub commit dfa22b348b70bb89d6d6ec0ff53973bacb4f4695.

The fix will be included in TensorFlow 2.6.0. This is the only affected version.

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Attribution This vulnerability has been reported by members of the Aivul Team from Qihoo 360.