Under certain conditions, Go code can trigger a segfault in string deallocation.
For string tensors,
C.TF_TString_Dealloc is called during garbage collection within a finalizer function. However, tensor structure isn't checked until encoding to avoid a performance penalty. The current method for dealloc assumes that encoding succeeded, but segfaults when a string tensor is garbage collected whose encoding failed (e.g., due to mismatched dimensions).
To fix this, the call to set the finalizer function is deferred until
NewTensor returns and, if encoding failed for a string tensor, deallocs are determined based on bytes written.
The fix will be included in TensorFlow 2.6.0. We will also cherrypick this commit on TensorFlow 2.5.1, which is the other affected version.
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This vulnerability has been reported externally via a fixing PR.