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RSA encryption: accept input=NULL if ilen=0

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In mbedtls_rsa_rsaes_oaep_encrypt and
mbedtls_rsa_rsaes_pkcs1_v15_encrypt, if the input length is 0 (which
is unusual and mostly useless, but permitted) then it is fine for the
input pointer to be NULL. Don't return an error in this case.

When `input` is NULL, `memcpy( p, input, ilen )` has undefined
behavior even if `ilen` is zero. So skip the `memcpy` call in this
case. Likewise, in `mbedtls_rsa_rsaes_oaep_decrypt` and
`mbedtls_rsa_rsaes_pkcs1_v15_decrypt`, skip the `memcpy` call if
`*olen` is zero.
This commit is contained in:
Gilles Peskine 2018-07-06 15:47:54 +02:00 committed by itayzafrir
parent ab1d7ab89f
commit 69e033aea0
1 changed files with 11 additions and 5 deletions
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8
library/rsa.c
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@ -1122,6 +1122,7 @@ int mbedtls_rsa_rsaes_oaep_encrypt( mbedtls_rsa_context *ctx,
p += hlen;
p += olen - 2 * hlen - 2 - ilen;
*p++ = 1;
if( ilen != 0 )
memcpy( p, input, ilen );
mbedtls_md_init( &md_ctx );
@ -1169,7 +1170,9 @@ int mbedtls_rsa_rsaes_pkcs1_v15_encrypt( mbedtls_rsa_context *ctx,
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
// We don't check p_rng because it won't be dereferenced here
if( f_rng == NULL || input == NULL || output == NULL )
if( f_rng == NULL || output == NULL )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
if( ilen != 0 && input == NULL )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
olen = ctx->len;
@ -1209,6 +1212,7 @@ int mbedtls_rsa_rsaes_pkcs1_v15_encrypt( mbedtls_rsa_context *ctx,
}
*p++ = 0;
if( ilen != 0 )
memcpy( p, input, ilen );
return( ( mode == MBEDTLS_RSA_PUBLIC )
@ -1373,6 +1377,7 @@ int mbedtls_rsa_rsaes_oaep_decrypt( mbedtls_rsa_context *ctx,
}
*olen = ilen - (p - buf);
if( *olen != 0 )
memcpy( output, p, *olen );
ret = 0;
@ -1471,6 +1476,7 @@ int mbedtls_rsa_rsaes_pkcs1_v15_decrypt( mbedtls_rsa_context *ctx,
}
*olen = ilen - (p - buf);
if( *olen != 0 )
memcpy( output, p, *olen );
ret = 0;