RSA: Fix another buffer overflow in PSS signature verification
Fix buffer overflow in RSA-PSS signature verification when the masking operation results in an all-zero buffer. This could happen at any key size.
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28a0c72795
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6a54b0240d
3 changed files with 17 additions and 10 deletions
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@ -6,6 +6,8 @@ Security
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* Fix buffer overflow in RSA-PSS verification when the hash is too
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large for the key size. Found by Seth Terashima, Qualcomm Product
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Security Initiative, Qualcomm Technologies Inc.
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* Fix buffer overflow in RSA-PSS verification when the unmasked
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data is all zeros.
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Features
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* Allow comments in test data files.
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@ -1319,10 +1319,11 @@ int mbedtls_rsa_rsassa_pss_verify_ext( mbedtls_rsa_context *ctx,
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int ret;
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size_t siglen;
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unsigned char *p;
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unsigned char *hash_start;
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unsigned char result[MBEDTLS_MD_MAX_SIZE];
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unsigned char zeros[8];
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unsigned int hlen;
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size_t slen, msb;
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size_t observed_salt_len, msb;
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const mbedtls_md_info_t *md_info;
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mbedtls_md_context_t md_ctx;
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unsigned char buf[MBEDTLS_MPI_MAX_SIZE];
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@ -1364,7 +1365,7 @@ int mbedtls_rsa_rsassa_pss_verify_ext( mbedtls_rsa_context *ctx,
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hlen = mbedtls_md_get_size( md_info );
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if( siglen < hlen + 2 )
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return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
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slen = siglen - hlen - 1; /* Currently length of salt + padding */
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hash_start = buf + siglen - hlen - 1;
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memset( zeros, 0, 8 );
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@ -1379,6 +1380,7 @@ int mbedtls_rsa_rsassa_pss_verify_ext( mbedtls_rsa_context *ctx,
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p++;
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siglen -= 1;
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}
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else
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if( buf[0] >> ( 8 - siglen * 8 + msb ) )
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return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
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@ -1389,25 +1391,24 @@ int mbedtls_rsa_rsassa_pss_verify_ext( mbedtls_rsa_context *ctx,
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return( ret );
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}
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mgf_mask( p, siglen - hlen - 1, p + siglen - hlen - 1, hlen, &md_ctx );
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mgf_mask( p, siglen - hlen - 1, hash_start, hlen, &md_ctx );
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buf[0] &= 0xFF >> ( siglen * 8 - msb );
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while( p < buf + siglen && *p == 0 )
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while( p < hash_start - 1 && *p == 0 )
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p++;
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if( p == buf + siglen ||
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if( p == hash_start ||
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*p++ != 0x01 )
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{
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mbedtls_md_free( &md_ctx );
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return( MBEDTLS_ERR_RSA_INVALID_PADDING );
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}
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/* Actual salt len */
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slen -= p - buf;
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observed_salt_len = hash_start - p;
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if( expected_salt_len != MBEDTLS_RSA_SALT_LEN_ANY &&
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slen != (size_t) expected_salt_len )
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observed_salt_len != (size_t) expected_salt_len )
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{
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mbedtls_md_free( &md_ctx );
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return( MBEDTLS_ERR_RSA_INVALID_PADDING );
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@ -1419,12 +1420,12 @@ int mbedtls_rsa_rsassa_pss_verify_ext( mbedtls_rsa_context *ctx,
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mbedtls_md_starts( &md_ctx );
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mbedtls_md_update( &md_ctx, zeros, 8 );
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mbedtls_md_update( &md_ctx, hash, hashlen );
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mbedtls_md_update( &md_ctx, p, slen );
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mbedtls_md_update( &md_ctx, p, observed_salt_len );
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mbedtls_md_finish( &md_ctx, result );
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mbedtls_md_free( &md_ctx );
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if( memcmp( p + slen, result, hlen ) == 0 )
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if( memcmp( hash_start, result, hlen ) == 0 )
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return( 0 );
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else
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return( MBEDTLS_ERR_RSA_VERIFY_FAILED );
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@ -819,3 +819,7 @@ RSASSA-PSS verify ext, 521-bit key, SHA-512, empty salt, bad signature
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depends_on:MBEDTLS_SHA512_C
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pkcs1_rsassa_pss_verify_ext:521:16:"0131b69860f3cb9bf85ea358fdf2bd2990f1b77a80d6a4fdf817a43dd896bdf7dd26af8ac0237f526e0d33b105c971fdbd4ffa9ece99fc469f31ecf429e8f562c1c3":16:"010001":MBEDTLS_MD_SHA512:MBEDTLS_MD_SHA512:MBEDTLS_MD_SHA512:0:"":"00471794655837da498cbf27242807b40593a353c707eb22fd2cc5a3259e728ac4f1df676043eeec8e16c1175b3d9ac8cae72ec1d5772dd69de71c5677f19031568e":MBEDTLS_ERR_RSA_INVALID_PADDING:MBEDTLS_ERR_RSA_INVALID_PADDING
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RSASSA-PSS verify ext, all-zero padding, automatic salt length
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depends_on:MBEDTLS_SHA256_C
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pkcs1_rsassa_pss_verify_ext:512:16:"00b076d23250816f9aab02307e452b97f0cae7598369b41624e8afc7971a59a13892f64b07eaa6ec928c160b2d6ec8f9d0dd5b63c8b3ac0767b4f65c892f56c10f":16:"010001":MBEDTLS_MD_NONE:MBEDTLS_MD_SHA256:MBEDTLS_MD_SHA256:MBEDTLS_RSA_SALT_LEN_ANY:"":"63a35294577c7e593170378175b7df27c293dae583ec2a971426eb2d66f2af483e897bfae5dc20300a9d61a3644e08c3aee61a463690a3498901563c46041056":MBEDTLS_ERR_RSA_INVALID_PADDING:MBEDTLS_ERR_RSA_INVALID_PADDING
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