diff options
| author | Dr. Stephen Henson <steve@openssl.org> | 2016-04-11 13:57:20 +0100 |
|---|---|---|
| committer | Dr. Stephen Henson <steve@openssl.org> | 2016-04-23 00:26:43 +0100 |
| commit | c62981390d6cf9e3d612c489b8b77c2913b25807 (patch) | |
| tree | 9b9c694270edbf0b45ee918c7f47d84713cb3e40 /crypto/asn1 | |
| parent | ddc606c914e72e770dbe8293a65585b7c3017bba (diff) | |
Harden ASN.1 BIO handling of large amounts of data.
If the ASN.1 BIO is presented with a large length field read it in
chunks of increasing size checking for EOF on each read. This prevents
small files allocating excessive amounts of data.
CVE-2016-2109
Thanks to Brian Carpenter for reporting this issue.
Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
Diffstat (limited to 'crypto/asn1')
| -rw-r--r-- | crypto/asn1/a_d2i_fp.c | 36 |
1 files changed, 26 insertions, 10 deletions
diff --git a/crypto/asn1/a_d2i_fp.c b/crypto/asn1/a_d2i_fp.c index 5ba6e1d1da..b030bf24dc 100644 --- a/crypto/asn1/a_d2i_fp.c +++ b/crypto/asn1/a_d2i_fp.c @@ -138,6 +138,7 @@ void *ASN1_item_d2i_fp(const ASN1_ITEM *it, FILE *in, void *x) #endif #define HEADER_SIZE 8 +#define ASN1_CHUNK_INITIAL_SIZE (16 * 1024) static int asn1_d2i_read_bio(BIO *in, BUF_MEM **pb) { BUF_MEM *b; @@ -216,29 +217,44 @@ static int asn1_d2i_read_bio(BIO *in, BUF_MEM **pb) /* suck in slen bytes of data */ want = slen; if (want > (len - off)) { + size_t chunk_max = ASN1_CHUNK_INITIAL_SIZE; + want -= (len - off); if (want > INT_MAX /* BIO_read takes an int length */ || len + want < len) { ASN1err(ASN1_F_ASN1_D2I_READ_BIO, ASN1_R_TOO_LONG); goto err; } - if (!BUF_MEM_grow_clean(b, len + want)) { - ASN1err(ASN1_F_ASN1_D2I_READ_BIO, ERR_R_MALLOC_FAILURE); - goto err; - } while (want > 0) { - i = BIO_read(in, &(b->data[len]), want); - if (i <= 0) { - ASN1err(ASN1_F_ASN1_D2I_READ_BIO, - ASN1_R_NOT_ENOUGH_DATA); + /* + * Read content in chunks of increasing size + * so we can return an error for EOF without + * having to allocate the entire content length + * in one go. + */ + size_t chunk = want > chunk_max ? chunk_max : want; + + if (!BUF_MEM_grow_clean(b, len + chunk)) { + ASN1err(ASN1_F_ASN1_D2I_READ_BIO, ERR_R_MALLOC_FAILURE); goto err; } + want -= chunk; + while (chunk > 0) { + i = BIO_read(in, &(b->data[len]), chunk); + if (i <= 0) { + ASN1err(ASN1_F_ASN1_D2I_READ_BIO, + ASN1_R_NOT_ENOUGH_DATA); + goto err; + } /* * This can't overflow because |len+want| didn't * overflow. */ - len += i; - want -= i; + len += i; + chunk -= i; + } + if (chunk_max < INT_MAX/2) + chunk_max *= 2; } } if (off + slen < off) { |