From bac809348a7313a5a5a53866848e7b6b56665f43 Mon Sep 17 00:00:00 2001 From: Gary Lockyer Date: Wed, 8 Apr 2020 10:46:44 +1200 Subject: [PATCH] CVE-2020-10704 libcli ldap: Check search request lengths. Check the search request lengths against the limits passed to ldap_decode. Credit to OSS-Fuzz REF: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=20454 BUG: https://bugzilla.samba.org/show_bug.cgi?id=14334 Signed-off-by: Gary Lockyer Reviewed-by: Andrew Bartlett Autobuild-User(master): Gary Lockyer Autobuild-Date(master): Mon May 4 04:40:10 UTC 2020 on sn-devel-184 --- lib/util/asn1.c | 7 +++++++ lib/util/asn1.h | 1 + libcli/ldap/ldap_message.c | 4 ++++ 3 files changed, 12 insertions(+) diff --git a/lib/util/asn1.c b/lib/util/asn1.c index a9caf6906f6..dc3f43f33f4 100644 --- a/lib/util/asn1.c +++ b/lib/util/asn1.c @@ -1175,3 +1175,10 @@ int asn1_peek_full_tag(DATA_BLOB blob, uint8_t tag, size_t *packet_size) *packet_size = size; return 0; } + +/* + * Get the length of the ASN.1 data + */ +size_t asn1_get_length(const struct asn1_data *asn1) { + return asn1->length; +} diff --git a/lib/util/asn1.h b/lib/util/asn1.h index fc365724e93..de92a767f14 100644 --- a/lib/util/asn1.h +++ b/lib/util/asn1.h @@ -106,5 +106,6 @@ bool asn1_extract_blob(struct asn1_data *asn1, TALLOC_CTX *mem_ctx, DATA_BLOB *pblob); void asn1_load_nocopy(struct asn1_data *data, uint8_t *buf, size_t len); int asn1_peek_full_tag(DATA_BLOB blob, uint8_t tag, size_t *packet_size); +size_t asn1_get_length(const struct asn1_data *asn1); #endif /* _ASN_1_H */ diff --git a/libcli/ldap/ldap_message.c b/libcli/ldap/ldap_message.c index d38fa0b3b61..69a48279532 100644 --- a/libcli/ldap/ldap_message.c +++ b/libcli/ldap/ldap_message.c @@ -1259,7 +1259,11 @@ _PUBLIC_ NTSTATUS ldap_decode(struct asn1_data *data, struct ldap_SearchRequest *r = &msg->r.SearchRequest; int sizelimit, timelimit; const char **attrs = NULL; + size_t request_size = asn1_get_length(data); msg->type = LDAP_TAG_SearchRequest; + if (request_size > limits->max_search_size) { + goto prot_err; + } if (!asn1_start_tag(data, tag)) goto prot_err; if (!asn1_read_OctetString_talloc(msg, data, &r->basedn)) goto prot_err; if (!asn1_read_enumerated(data, (int *)(void *)&(r->scope))) goto prot_err;