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Fix misuse of MD API in SSL constant-flow HMAC

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The sequence of calls starts-update-starts-update-finish is not a
guaranteed valid way to abort an operation and start a new one. Our
software implementation just happens to support it, but alt
implementations may very well not support it.

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
This commit is contained in:
Manuel Pégourié-Gonnard
2021-05-17 12:28:08 +02:00
parent 8ce4ab18ab
commit 21bfbdd703
2 changed files with 8 additions and 0 deletions
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library/ssl_msg.c
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@ -1241,6 +1241,9 @@ MBEDTLS_STATIC_TESTABLE int mbedtls_ssl_cf_hmac(
MD_CHK( mbedtls_md_update( ctx, data + offset, 1 ) );
}
/* The context needs to finish() before it starts() again */
MD_CHK( mbedtls_md_finish( ctx, aux_out ) );
/* Now compute HASH(okey + inner_hash) */
MD_CHK( mbedtls_md_starts( ctx ) );
MD_CHK( mbedtls_md_update( ctx, okey, block_size ) );