CVE-2020-15211

Advisory

Tensorflow versions 1.15.4, 2.0.3, 2.1.2, 2.2.1, and 2.3.1 include a fix for CVE-2020-15211: In tensorflow-lite before versions 1.15.4, 2.0.3, 2.1.2, 2.2.1 and 2.3.1, saved models in the flatbuffer format use a double indexing scheme: a model has a set of subgraphs, each subgraph has a set of operators and each operator has a set of input/output tensors. The flatbuffer format uses indices for the tensors, indexing into an array of tensors that is owned by the subgraph. This results in a pattern of double array indexing when trying to get the data of each tensor. However, some operators can have some tensors be optional. To handle this scenario, the flatbuffer model uses a negative "-1" value as index for these tensors. This results in special casing during validation at model loading time. Unfortunately, this means that the "-1" index is a valid tensor index for any operator, including those that don't expect optional inputs and including for output tensors. Thus, this allows writing and reading from outside the bounds of heap allocated arrays, although only at a specific offset from the start of these arrays. This results in both read and write gadgets, albeit very limited in scope. The issue was patched in several commits (46d5b0852, 00302787b7, e11f5558, cd31fd0ce, 1970c21, and fff2c83). A potential workaround would be to add a custom "Verifier" to the model loading code to ensure that only operators which accept optional inputs use the "-1" special value and only for the tensors that they expect to be optional. Since this allow-list type approach is error-prone, it's advised upgrading to the patched code.

Affected package

Affected versions

Fixed versions

Vulnerability changelog

Bug Fixes and Other Changes
* Fixes an undefined behavior causing a segfault in `tf.raw_ops.Switch`
([CVE-2020-15190](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-15190))
* Fixes three vulnerabilities in conversion to DLPack format
([CVE-2020-15191](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-15191),
[CVE-2020-15192](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-15192),
[CVE-2020-15193](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-15193))
* Fixes two vulnerabilities in `SparseFillEmptyRowsGrad`
([CVE-2020-15194](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-15194),
[CVE-2020-15195](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-15195))
* Fixes an integer truncation vulnerability in code using the work sharder API
([CVE-2020-15202](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-15202))
* Fixes a format string vulnerability in `tf.strings.as_string`
([CVE-2020-15203](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-15203))
* Fixes segfault raised by calling session-only ops in eager mode
([CVE-2020-15204](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-15204))
* Fixes data leak and potential ASLR violation from `tf.raw_ops.StringNGrams`
([CVE-2020-15205](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-15205))
* Fixes segfaults caused by incomplete `SavedModel` validation
([CVE-2020-15206](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-15206))
* Fixes a data corruption due to a bug in negative indexing support in TFLite
([CVE-2020-15207](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-15207))
* Fixes a data corruption due to dimension mismatch in TFLite
([CVE-2020-15208](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-15208))
* Fixes several vulnerabilities in TFLite saved model format
([CVE-2020-15209](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-15209),
[CVE-2020-15210](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-15210),
[CVE-2020-15211](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-15211))
* Updates `sqlite3` to `3.33.00` to handle
[CVE-2020-9327](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-9327),
[CVE-2020-11655](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-11655),
[CVE-2020-11656](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-11656),
[CVE-2020-13434](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-13434),
[CVE-2020-13435](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-13435),
[CVE-2020-13630](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-13630),
[CVE-2020-13631](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-13631),
[CVE-2020-13871](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-13871),
and
[CVE-2020-15358](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-15358).
* Pins `numpy` to 1.18.5 to prevent ABI breakage when compiling code that uses
both NumPy and TensorFlow headers.

Resources

• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-15211
• https://github.com/tensorflow/tensorflow/commit/e11f55585f614645b360563072ffeb5c3eeff162
• https://github.com/tensorflow/tensorflow/commit/cd31fd0ce0449a9e0f83dcad08d6ed7f1d6bef3f
• https://github.com/tensorflow/tensorflow/commit/46d5b0852528ddfd614ded79bccc75589f801bd9
• https://github.com/tensorflow/tensorflow/commit/00302787b788c5ff04cb6f62aed5a74d936e86c0
• https://github.com/tensorflow/tensorflow/security/advisories/GHSA-cvpc-8phh-8f45
• https://github.com/tensorflow/tensorflow/commit/fff2c8326280c07733828f990548979bdc893859
• https://github.com/tensorflow/tensorflow/releases/tag/v2.3.1
• https://github.com/tensorflow/tensorflow/commit/1970c2158b1ffa416d159d03c3370b9a462aee35
• http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00065.html