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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`, 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 Andrzej Kurek
parent fb236739da
commit 004f87b98d
1 changed files with 6 additions and 3 deletions
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9
library/rsa.c
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@ -1171,7 +1171,8 @@ int mbedtls_rsa_rsaes_oaep_encrypt( mbedtls_rsa_context *ctx,
p += hlen; p += hlen;
p += olen - 2 * hlen - 2 - ilen; p += olen - 2 * hlen - 2 - ilen;
*p++ = 1; *p++ = 1;
memcpy( p, input, ilen ); if( ilen != 0 )
memcpy( p, input, ilen );
mbedtls_md_init( &md_ctx ); mbedtls_md_init( &md_ctx );
if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 ) if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 )
@ -1263,7 +1264,8 @@ int mbedtls_rsa_rsaes_pkcs1_v15_encrypt( mbedtls_rsa_context *ctx,
} }
*p++ = 0; *p++ = 0;
memcpy( p, input, ilen ); if( ilen != 0 )
memcpy( p, input, ilen );
return( ( mode == MBEDTLS_RSA_PUBLIC ) return( ( mode == MBEDTLS_RSA_PUBLIC )
? mbedtls_rsa_public( ctx, output, output ) ? mbedtls_rsa_public( ctx, output, output )
@ -1441,7 +1443,8 @@ int mbedtls_rsa_rsaes_oaep_decrypt( mbedtls_rsa_context *ctx,
} }
*olen = ilen - (p - buf); *olen = ilen - (p - buf);
memcpy( output, p, *olen ); if( *olen != 0 )
memcpy( output, p, *olen );
ret = 0; ret = 0;
cleanup: cleanup: