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Fix AES OCB encrypt/decrypt for x86 AES-NI
aesni_ocb_encrypt and aesni_ocb_decrypt operate by having a fast-path that performs operations on 6 16-byte blocks concurrently (the "grandloop") and then proceeds to handle the "short" tail (which can be anywhere from 0 to 5 blocks) that remain. As part of initialization, the assembly initializes $len to the true length, less 96 bytes and converts it to a pointer so that the $inp can be compared to it. Each iteration of "grandloop" checks to see if there's a full 96-byte chunk to process, and if so, continues. Once this has been exhausted, it falls through to "short", which handles the remaining zero to five blocks. Unfortunately, the jump at the end of "grandloop" had a fencepost error, doing a `jb` ("jump below") rather than `jbe` (jump below or equal). This should be `jbe`, as $inp is pointing to the *end* of the chunk currently being handled. If $inp == $len, that means that there's a whole 96-byte chunk waiting to be handled. If $inp > $len, then there's 5 or fewer 16-byte blocks left to be handled, and the fall-through is intended. The net effect of `jb` instead of `jbe` is that the last 16-byte block of the last 96-byte chunk was completely omitted. The contents of `out` in this position were never written to. Additionally, since those bytes were never processed, the authentication tag generated is also incorrect. The same fencepost error, and identical logic, exists in both aesni_ocb_encrypt and aesni_ocb_decrypt. This addresses CVE-2022-2097. Co-authored-by: Alejandro Sedeño <asedeno@google.com> Co-authored-by: David Benjamin <davidben@google.com> Reviewed-by: Paul Dale <pauli@openssl.org> Reviewed-by: Tomas Mraz <tomas@openssl.org> (cherry picked from commit 6ebf6d5)
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