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Fix buffer overreads in mbedtls_pem_read_buffer()

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This commit is contained in:
Andres AG 2016-10-24 11:23:36 +01:00
parent c1d54bb7b2
commit d3cbc15951
2 changed files with 18 additions and 9 deletions
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7
ChangeLog
View file

@ -1,5 +1,12 @@
mbed TLS ChangeLog (Sorted per branch, date)
= mbed TLS 1.3.x branch released xxxx-xx-xx
Bugfix
* Fixed multiple buffer overreads in mbedtls_pem_read_buffer() when parsing
the input string in pem format to extract the different components. Found
by Eyal Itkin.
= mbed TLS 1.3.18 branch 2016-10-17
Security

20
library/pem.c
View file

@ -250,7 +250,7 @@ int pem_read_buffer( pem_context *ctx, const char *header, const char *footer,
enc = 0;
if( memcmp( s1, "Proc-Type: 4,ENCRYPTED", 22 ) == 0 )
if( s2 - s1 >= 22 && memcmp( s1, "Proc-Type: 4,ENCRYPTED", 22 ) == 0 )
{
#if defined(POLARSSL_MD5_C) && defined(POLARSSL_CIPHER_MODE_CBC) && \
( defined(POLARSSL_DES_C) || defined(POLARSSL_AES_C) )
@ -263,22 +263,22 @@ int pem_read_buffer( pem_context *ctx, const char *header, const char *footer,
#if defined(POLARSSL_DES_C)
if( memcmp( s1, "DEK-Info: DES-EDE3-CBC,", 23 ) == 0 )
if( s2 - s1 >= 23 && memcmp( s1, "DEK-Info: DES-EDE3-CBC,", 23 ) == 0 )
{
enc_alg = POLARSSL_CIPHER_DES_EDE3_CBC;
s1 += 23;
if( pem_get_iv( s1, pem_iv, 8 ) != 0 )
if( s2 - s1 < 16 || pem_get_iv( s1, pem_iv, 8 ) != 0 )
return( POLARSSL_ERR_PEM_INVALID_ENC_IV );
s1 += 16;
}
else if( memcmp( s1, "DEK-Info: DES-CBC,", 18 ) == 0 )
else if( s2 - s1 >= 18 && memcmp( s1, "DEK-Info: DES-CBC,", 18 ) == 0 )
{
enc_alg = POLARSSL_CIPHER_DES_CBC;
s1 += 18;
if( pem_get_iv( s1, pem_iv, 8) != 0 )
if( s2 - s1 < 16 || pem_get_iv( s1, pem_iv, 8) != 0 )
return( POLARSSL_ERR_PEM_INVALID_ENC_IV );
s1 += 16;
@ -286,9 +286,11 @@ int pem_read_buffer( pem_context *ctx, const char *header, const char *footer,
#endif /* POLARSSL_DES_C */
#if defined(POLARSSL_AES_C)
if( memcmp( s1, "DEK-Info: AES-", 14 ) == 0 )
if( s2 - s1 >= 14 && memcmp( s1, "DEK-Info: AES-", 14 ) == 0 )
{
if( memcmp( s1, "DEK-Info: AES-128-CBC,", 22 ) == 0 )
if( s2 - s1 < 22 )
return( POLARSSL_ERR_PEM_UNKNOWN_ENC_ALG );
else if( memcmp( s1, "DEK-Info: AES-128-CBC,", 22 ) == 0 )
enc_alg = POLARSSL_CIPHER_AES_128_CBC;
else if( memcmp( s1, "DEK-Info: AES-192-CBC,", 22 ) == 0 )
enc_alg = POLARSSL_CIPHER_AES_192_CBC;
@ -298,7 +300,7 @@ int pem_read_buffer( pem_context *ctx, const char *header, const char *footer,
return( POLARSSL_ERR_PEM_UNKNOWN_ENC_ALG );
s1 += 22;
if( pem_get_iv( s1, pem_iv, 16 ) != 0 )
if( s2 - s1 < 32 || pem_get_iv( s1, pem_iv, 16 ) != 0 )
return( POLARSSL_ERR_PEM_INVALID_ENC_IV );
s1 += 32;
@ -317,7 +319,7 @@ int pem_read_buffer( pem_context *ctx, const char *header, const char *footer,
( POLARSSL_AES_C || POLARSSL_DES_C ) */
}
if( s1 == s2 )
if( s1 >= s2 )
return( POLARSSL_ERR_PEM_INVALID_DATA );
len = 0;