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Fix NULL+0 undefined behavior in ECB encryption and decryption

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psa_cipher_encrypt() and psa_cipher_decrypt() sometimes add a zero offset to
a null pointer when the cipher does not use an IV. This is undefined
behavior, although it works as naively expected on most platforms. This
can cause a crash with modern Clang+ASan (depending on compiler optimizations).

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This commit is contained in:
Gilles Peskine
2022-11-23 14:15:57 +01:00
parent 1d1d53622f
commit 42649d9270
5 changed files with 58 additions and 14 deletions
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23
library/psa_crypto_cipher.c
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@@ -516,10 +516,10 @@ psa_status_t mbedtls_psa_cipher_encrypt(
if( status != PSA_SUCCESS )
goto exit;
status = mbedtls_psa_cipher_finish( &operation,
output + update_output_length,
output_size - update_output_length,
&finish_output_length );
status = mbedtls_psa_cipher_finish(
&operation,
mbedtls_buffer_offset( output, update_output_length ),
output_size - update_output_length, &finish_output_length );
if( status != PSA_SUCCESS )
goto exit;
@@ -563,17 +563,20 @@ psa_status_t mbedtls_psa_cipher_decrypt(
goto exit;
}
status = mbedtls_psa_cipher_update( &operation, input + operation.iv_length,
input_length - operation.iv_length,
output, output_size, &olength );
status = mbedtls_psa_cipher_update(
&operation,
mbedtls_buffer_offset_const( input, operation.iv_length ),
input_length - operation.iv_length,
output, output_size, &olength );
if( status != PSA_SUCCESS )
goto exit;
accumulated_length = olength;
status = mbedtls_psa_cipher_finish( &operation, output + accumulated_length,
output_size - accumulated_length,
&olength );
status = mbedtls_psa_cipher_finish(
&operation,
mbedtls_buffer_offset( output, accumulated_length ),
output_size - accumulated_length, &olength );
if( status != PSA_SUCCESS )
goto exit;