"George Garner (online)" <ggarner_onl...@gmgsystemsinc.com> writes:
[...]
> 3. Where is the p_len/group_order parameter validated? In
> kex_method_diffie_hellman_group_exchange_sha256_key_exchange it is
> converted from network byte order and accepted at face value. What
> happens if a malicious packet is received with a bogus value for
> p_len?
Maybe I miss something, but it looks like this defect (blindly trust
various 32-bit length that was sent remote side and don't verify if it
fits buffer) is *everywhere* in libssh2. I've sent some patches for
kex.c via gh pull request, but quickly discovered it is much worse. Very
WIP (and incomplete) patch for *other* files is attached; unfortunately,
in most cases, I have no idea how such errors should be handled within libssh2,
don't know libssh2 code base well enough, so I give up at this.
Note that in early connection setup "malicious server" is not required,
"malicious MITM" can insert broken packets as well.
In general, please re-review all `grep ntoh -r src/`, in many cases
surrounding code looks problematic in one way or other.
---
Changelog:
v2: fixed obvious errors
Note: This is still NOT COMPLETE work, all XXX comment must be reviewed and acted upon.
src/agent.c | 32 ++++++++--------
src/channel.c | 10 ++++-
src/hostkey.c | 19 +++++++--
src/kex.c | 43 +++++++++++----------
src/packet.c | 45 +++++++++++++++++-----
src/publickey.c | 117 +++++++++++++++++++++++++++++++++++++++++++-------------
src/session.c | 2 +
src/sftp.c | 42 ++++++++++++++++----
src/sftp.h | 1 +
src/userauth.c | 32 ++++++++++++++++
10 files changed, 260 insertions(+), 83 deletions(-)
diff --git a/src/agent.c b/src/agent.c
index c2ba422..255b63d 100644
--- a/src/agent.c
+++ b/src/agent.c
@@ -449,12 +449,12 @@ agent_sign(LIBSSH2_SESSION *session, unsigned char **sig, size_t *sig_len,
goto error;
}
method_len = _libssh2_ntohu32(s);
- s += 4;
- len -= method_len;
- if (len < 0) {
+ if (method_len < 0 || len < method_len) {
rc = LIBSSH2_ERROR_AGENT_PROTOCOL;
goto error;
}
+ s += 4;
+ len -= method_len;
s += method_len;
/* Read the signature */
@@ -464,12 +464,12 @@ agent_sign(LIBSSH2_SESSION *session, unsigned char **sig, size_t *sig_len,
goto error;
}
*sig_len = _libssh2_ntohu32(s);
- s += 4;
- len -= *sig_len;
- if (len < 0) {
+ if ((size_t)len < *sig_len) {
rc = LIBSSH2_ERROR_AGENT_PROTOCOL;
goto error;
}
+ len -= *sig_len;
+ s += 4;
*sig = LIBSSH2_ALLOC(session, *sig_len);
if (!*sig) {
@@ -558,15 +558,15 @@ agent_list_identities(LIBSSH2_AGENT *agent)
goto error;
}
identity->external.blob_len = _libssh2_ntohu32(s);
- s += 4;
-
- /* Read the blob */
- len -= identity->external.blob_len;
- if (len < 0) {
+ if ((size_t)len < identity->external.blob_len) {
rc = LIBSSH2_ERROR_AGENT_PROTOCOL;
LIBSSH2_FREE(agent->session, identity);
goto error;
}
+ s += 4;
+
+ /* Read the blob */
+ len -= identity->external.blob_len;
identity->external.blob = LIBSSH2_ALLOC(agent->session,
identity->external.blob_len);
@@ -587,16 +587,16 @@ agent_list_identities(LIBSSH2_AGENT *agent)
goto error;
}
comment_len = _libssh2_ntohu32(s);
- s += 4;
-
- /* Read the comment */
- len -= comment_len;
- if (len < 0) {
+ if (comment_len < 0 || len < comment_len) {
rc = LIBSSH2_ERROR_AGENT_PROTOCOL;
LIBSSH2_FREE(agent->session, identity->external.blob);
LIBSSH2_FREE(agent->session, identity);
goto error;
}
+ s += 4;
+
+ /* Read the comment */
+ len -= comment_len;
identity->external.comment = LIBSSH2_ALLOC(agent->session,
comment_len + 1);
diff --git a/src/channel.c b/src/channel.c
index 32d914d..38572be 100644
--- a/src/channel.c
+++ b/src/channel.c
@@ -225,6 +225,7 @@ _libssh2_channel_open(LIBSSH2_SESSION * session, const char *channel_type,
}
if (session->open_state == libssh2_NB_state_sent) {
+ unsigned char *end;
rc = _libssh2_packet_requirev(session, reply_codes,
&session->open_data,
&session->open_data_len, 1,
@@ -238,7 +239,11 @@ _libssh2_channel_open(LIBSSH2_SESSION * session, const char *channel_type,
goto channel_error;
}
+ end = session->open_data + session->open_data_len;
+
if (session->open_data[0] == SSH_MSG_CHANNEL_OPEN_CONFIRMATION) {
+ if (13+4 > (end - session->open_data))
+ goto channel_error;
session->open_channel->remote.id =
_libssh2_ntohu32(session->open_data + 5);
session->open_channel->local.window_size =
@@ -265,7 +270,8 @@ _libssh2_channel_open(LIBSSH2_SESSION * session, const char *channel_type,
return session->open_channel;
}
- if (session->open_data[0] == SSH_MSG_CHANNEL_OPEN_FAILURE) {
+ if (session->open_data[0] == SSH_MSG_CHANNEL_OPEN_FAILURE &&
+ 4 <= (end - (session->open_data + 5))) {
unsigned int reason_code = _libssh2_ntohu32(session->open_data + 5);
switch (reason_code) {
case SSH_OPEN_ADMINISTRATIVELY_PROHIBITED:
@@ -1399,6 +1405,7 @@ _libssh2_channel_flush(LIBSSH2_CHANNEL *channel, int streamid)
if (((packet_type == SSH_MSG_CHANNEL_DATA)
|| (packet_type == SSH_MSG_CHANNEL_EXTENDED_DATA))
+ && packet->data_len >= 5 + (packet_type == SSH_MSG_CHANNEL_EXTENDED_DATA ? 4 : 0)
&& (_libssh2_ntohu32(packet->data + 1) == channel->local.id)) {
/* It's our channel at least */
long packet_stream_id =
@@ -1418,6 +1425,7 @@ _libssh2_channel_flush(LIBSSH2_CHANNEL *channel, int streamid)
bytes_to_flush, packet_stream_id,
channel->local.id, channel->remote.id);
+ /* XXX assert(packet->data_len >= 13); XXX */
/* It's one of the streams we wanted to flush */
channel->flush_refund_bytes += packet->data_len - 13;
channel->flush_flush_bytes += bytes_to_flush;
diff --git a/src/hostkey.c b/src/hostkey.c
index 2a0a8f9..7b780e2 100644
--- a/src/hostkey.c
+++ b/src/hostkey.c
@@ -66,31 +66,42 @@ hostkey_method_ssh_rsa_init(LIBSSH2_SESSION * session,
libssh2_rsa_ctx *rsactx;
const unsigned char *s, *e, *n;
unsigned long len, e_len, n_len;
+ const unsigned char *end = hostkey_data + hostkey_data_len;
int ret;
- (void) hostkey_data_len;
-
if (*abstract) {
hostkey_method_ssh_rsa_dtor(session, abstract);
*abstract = NULL;
}
s = hostkey_data;
+ if (4 > end - s)
+ return -1;
len = _libssh2_ntohu32(s);
s += 4;
+ if (len > (size_t)(end - s))
+ return -1;
if (len != 7 || strncmp((char *) s, "ssh-rsa", 7) != 0) {
return -1;
}
- s += 7;
+ s += len;
+ if (4 > end - s)
+ return -1;
e_len = _libssh2_ntohu32(s);
s += 4;
+ if (e_len > (size_t)(end - s))
+ return -1;
e = s;
s += e_len;
+ if (4 > end - s)
+ return -1;
n_len = _libssh2_ntohu32(s);
s += 4;
+ if (n_len > (size_t)(end - s))
+ return -1;
n = s;
ret = _libssh2_rsa_new(&rsactx, e, e_len, n, n_len, NULL, 0,
@@ -181,6 +192,8 @@ hostkey_method_ssh_rsa_sig_verify(LIBSSH2_SESSION * session,
(void) session;
/* Skip past keyname_len(4) + keyname(7){"ssh-rsa"} + signature_len(4) */
+ if (15 > sig_len)
+ return -1;
sig += 15;
sig_len -= 15;
return _libssh2_rsa_sha1_verify(rsactx, sig, sig_len, m, m_len);
diff --git a/src/kex.c b/src/kex.c
index 40dbeab..2381d52 100644
--- a/src/kex.c
+++ b/src/kex.c
@@ -2463,21 +2463,20 @@ static int kex_agree_comp(LIBSSH2_SESSION *session,
* within the given packet.
*/
static int kex_string_pair(unsigned char **sp, /* parsing position */
- unsigned char *data, /* start pointer to packet */
- size_t data_len, /* size of total packet */
+ unsigned char *end, /* end of packet */
size_t *lenp, /* length of the string */
unsigned char **strp) /* pointer to string start */
{
unsigned char *s = *sp;
- *lenp = _libssh2_ntohu32(s);
- /* the length of the string must fit within the current pointer and the
- end of the packet */
- if (*lenp > (data_len - (s - data) -4))
+ if (4 > end - s)
return 1;
- *strp = s + 4;
- s += 4 + *lenp;
-
+ *lenp = _libssh2_ntohu32(s);
+ s += 4;
+ if (*lenp > (size_t)(end - s))
+ return 1;
+ *strp = s;
+ s += *lenp;
*sp = s;
return 0;
}
@@ -2493,6 +2492,10 @@ static int kex_agree_methods(LIBSSH2_SESSION * session, unsigned char *data,
size_t kex_len, hostkey_len, crypt_cs_len, crypt_sc_len, comp_cs_len;
size_t comp_sc_len, mac_cs_len, mac_sc_len;
unsigned char *s = data;
+ unsigned char *end = data + data_len;
+
+ if (1 + 16 > end - s)
+ return -1;
/* Skip packet_type, we know it already */
s++;
@@ -2501,21 +2504,24 @@ static int kex_agree_methods(LIBSSH2_SESSION * session, unsigned char *data,
s += 16;
/* Locate each string */
- if(kex_string_pair(&s, data, data_len, &kex_len, &kex))
+ if(kex_string_pair(&s, end, &kex_len, &kex))
+ return -1;
+ if(kex_string_pair(&s, end, &hostkey_len, &hostkey))
return -1;
- if(kex_string_pair(&s, data, data_len, &hostkey_len, &hostkey))
+ if(kex_string_pair(&s, end, &crypt_cs_len, &crypt_cs))
return -1;
- if(kex_string_pair(&s, data, data_len, &crypt_cs_len, &crypt_cs))
+ if(kex_string_pair(&s, end, &crypt_sc_len, &crypt_sc))
return -1;
- if(kex_string_pair(&s, data, data_len, &crypt_sc_len, &crypt_sc))
+ if(kex_string_pair(&s, end, &mac_cs_len, &mac_cs))
return -1;
- if(kex_string_pair(&s, data, data_len, &mac_cs_len, &mac_cs))
+ if(kex_string_pair(&s, end, &mac_sc_len, &mac_sc))
return -1;
- if(kex_string_pair(&s, data, data_len, &mac_sc_len, &mac_sc))
+ if(kex_string_pair(&s, end, &comp_cs_len, &comp_cs))
return -1;
- if(kex_string_pair(&s, data, data_len, &comp_cs_len, &comp_cs))
+ if(kex_string_pair(&s, end, &comp_sc_len, &comp_sc))
return -1;
- if(kex_string_pair(&s, data, data_len, &comp_sc_len, &comp_sc))
+
+ if (1 > end - s)
return -1;
/* If the server sent an optimistic packet, assume that it guessed wrong.
@@ -2524,9 +2530,6 @@ static int kex_agree_methods(LIBSSH2_SESSION * session, unsigned char *data,
session->burn_optimistic_kexinit = *(s++);
/* Next uint32 in packet is all zeros (reserved) */
- if (data_len < (unsigned) (s - data))
- return -1; /* short packet */
-
if (kex_agree_kex_hostkey(session, kex, kex_len, hostkey, hostkey_len)) {
return -1;
}
diff --git a/src/packet.c b/src/packet.c
index 5f1feb8..3659daa 100644
--- a/src/packet.c
+++ b/src/packet.c
@@ -85,10 +85,12 @@ packet_queue_listener(LIBSSH2_SESSION * session, unsigned char *data,
char failure_code = SSH_OPEN_ADMINISTRATIVELY_PROHIBITED;
int rc;
- (void) datalen;
-
if (listen_state->state == libssh2_NB_state_idle) {
unsigned char *s = data + (sizeof("forwarded-tcpip") - 1) + 5;
+ unsigned char *end = data + datalen;
+ if (4*4 > (end - s)) {
+ return 0; /* XXX ??? XXX */
+ }
listen_state->sender_channel = _libssh2_ntohu32(s);
s += 4;
@@ -99,15 +101,27 @@ packet_queue_listener(LIBSSH2_SESSION * session, unsigned char *data,
listen_state->host_len = _libssh2_ntohu32(s);
s += 4;
+ if (listen_state->host_len > (size_t)(end - s)) {
+ return 0; /* XXX ??? XXX */
+ }
listen_state->host = s;
s += listen_state->host_len;
+ if (4*2 > (end - s)) {
+ return 0; /* XXX ??? XXX */
+ }
listen_state->port = _libssh2_ntohu32(s);
s += 4;
listen_state->shost_len = _libssh2_ntohu32(s);
s += 4;
+ if (listen_state->shost_len > (size_t)(end - s)) {
+ return 0; /* XXX ??? XXX */
+ }
listen_state->shost = s;
s += listen_state->shost_len;
+ if (4 > (end - s)) {
+ return 0; /* XXX ??? XXX */
+ }
listen_state->sport = _libssh2_ntohu32(s);
_libssh2_debug(session, LIBSSH2_TRACE_CONN,
@@ -271,10 +285,12 @@ packet_x11_open(LIBSSH2_SESSION * session, unsigned char *data,
LIBSSH2_CHANNEL *channel = x11open_state->channel;
int rc;
- (void) datalen;
-
if (x11open_state->state == libssh2_NB_state_idle) {
unsigned char *s = data + (sizeof("x11") - 1) + 5;
+ unsigned char *end = data + datalen;
+ if (4*4 > (end - s)) {
+ return 0; /* XXX ??? XXX */
+ }
x11open_state->sender_channel = _libssh2_ntohu32(s);
s += 4;
x11open_state->initial_window_size = _libssh2_ntohu32(s);
@@ -283,8 +299,14 @@ packet_x11_open(LIBSSH2_SESSION * session, unsigned char *data,
s += 4;
x11open_state->shost_len = _libssh2_ntohu32(s);
s += 4;
+ if (x11open_state->shost_len > (size_t)(end - s)) {
+ return 0; /* XXX ??? XXX */
+ }
x11open_state->shost = s;
s += x11open_state->shost_len;
+ if (4 > (end - s)) {
+ return 0; /* XXX ??? XXX */
+ }
x11open_state->sport = _libssh2_ntohu32(s);
_libssh2_debug(session, LIBSSH2_TRACE_CONN,
@@ -807,22 +829,26 @@ _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data,
else if (len == sizeof("exit-signal") - 1
&& !memcmp("exit-signal", data + 9,
sizeof("exit-signal") - 1)) {
+ unsigned char *end = data + datalen;
+ unsigned char *s = data + 9 + sizeof("exit-signal");
/* command terminated due to signal */
if(datalen >= 20)
channelp = _libssh2_channel_locate(session, channel);
- if (channelp) {
+ if (channelp && end - s >= 4) {
/* set signal name (without SIG prefix) */
- uint32_t namelen =
- _libssh2_ntohu32(data + 9 + sizeof("exit-signal"));
+ uint32_t namelen = _libssh2_ntohu32(s);
+ s += 4;
+ if (namelen > (size_t)(end - s))
+ /* XXX ??? XXX */;
+ else {
channelp->exit_signal =
LIBSSH2_ALLOC(session, namelen + 1);
if (!channelp->exit_signal)
rc = _libssh2_error(session, LIBSSH2_ERROR_ALLOC,
"memory for signal name");
else {
- memcpy(channelp->exit_signal,
- data + 13 + sizeof("exit_signal"), namelen);
+ memcpy(channelp->exit_signal, s, namelen);
channelp->exit_signal[namelen] = '\0';
/* TODO: save error message and language tag */
_libssh2_debug(session, LIBSSH2_TRACE_CONN,
@@ -832,6 +858,7 @@ _libssh2_packet_add(LIBSSH2_SESSION * session, unsigned char *data,
channelp->local.id,
channelp->remote.id);
}
+ }
}
}
diff --git a/src/publickey.c b/src/publickey.c
index bfee0a8..d19efb7 100644
--- a/src/publickey.c
+++ b/src/publickey.c
@@ -247,6 +247,7 @@ publickey_response_success(LIBSSH2_PUBLICKEY * pkey)
switch (response) {
case LIBSSH2_PUBLICKEY_RESPONSE_STATUS:
/* Error, or processing complete */
+ if (data_len >= 4)
{
unsigned long status = _libssh2_ntohu32(s);
@@ -258,6 +259,7 @@ publickey_response_success(LIBSSH2_PUBLICKEY * pkey)
publickey_status_error(pkey, session, status);
return -1;
}
+ /* fallthru */
default:
LIBSSH2_FREE(session, data);
if (response < 0) {
@@ -403,6 +405,7 @@ static LIBSSH2_PUBLICKEY *publickey_init(LIBSSH2_SESSION *session)
if (session->pkeyInit_state == libssh2_NB_state_sent3) {
while (1) {
unsigned char *s;
+ unsigned char *end;
rc = publickey_packet_receive(session->pkeyInit_pkey,
&session->pkeyInit_data,
&session->pkeyInit_data_len);
@@ -419,6 +422,7 @@ static LIBSSH2_PUBLICKEY *publickey_init(LIBSSH2_SESSION *session)
}
s = session->pkeyInit_data;
+ end = session->pkeyInit_data + session->pkeyInit_data_len;
if ((response =
publickey_response_id(&s, session->pkeyInit_data_len)) < 0) {
_libssh2_error(session, LIBSSH2_ERROR_PUBLICKEY_PROTOCOL,
@@ -432,19 +436,33 @@ static LIBSSH2_PUBLICKEY *publickey_init(LIBSSH2_SESSION *session)
{
unsigned long status, descr_len, lang_len;
- status = _libssh2_ntohu32(s);
- s += 4;
- descr_len = _libssh2_ntohu32(s);
- s += 4;
- /* description starts here */
- s += descr_len;
- lang_len = _libssh2_ntohu32(s);
- s += 4;
- /* lang starts here */
- s += lang_len;
-
- if (s >
- session->pkeyInit_data + session->pkeyInit_data_len) {
+ if (4*2 > end - s)
+ s = NULL;
+ else {
+ status = _libssh2_ntohu32(s);
+ s += 4;
+ descr_len = _libssh2_ntohu32(s);
+ s += 4;
+ /* description starts here */
+ if (descr_len > (size_t)(end - s))
+ s = NULL;
+ else {
+ s += descr_len;
+ if (4 > end - s)
+ s = NULL;
+ else {
+ lang_len = _libssh2_ntohu32(s);
+ s += 4;
+ /* lang starts here */
+ if (lang_len > (size_t)(end - s))
+ s = NULL;
+ else
+ s += lang_len;
+ }
+ }
+ }
+
+ if (s == NULL) {
_libssh2_error(session,
LIBSSH2_ERROR_PUBLICKEY_PROTOCOL,
"Malformed publickey subsystem packet");
@@ -810,6 +828,7 @@ libssh2_publickey_list_fetch(LIBSSH2_PUBLICKEY * pkey, unsigned long *num_keys,
}
while (1) {
+ unsigned char *end;
rc = publickey_packet_receive(pkey, &pkey->listFetch_data,
&pkey->listFetch_data_len);
if (rc == LIBSSH2_ERROR_EAGAIN) {
@@ -822,6 +841,7 @@ libssh2_publickey_list_fetch(LIBSSH2_PUBLICKEY * pkey, unsigned long *num_keys,
}
pkey->listFetch_s = pkey->listFetch_data;
+ end = pkey->listFetch_data + pkey->listFetch_data_len;
if ((response =
publickey_response_id(&pkey->listFetch_s,
pkey->listFetch_data_len)) < 0) {
@@ -836,19 +856,34 @@ libssh2_publickey_list_fetch(LIBSSH2_PUBLICKEY * pkey, unsigned long *num_keys,
{
unsigned long status, descr_len, lang_len;
- status = _libssh2_ntohu32(pkey->listFetch_s);
- pkey->listFetch_s += 4;
- descr_len = _libssh2_ntohu32(pkey->listFetch_s);
- pkey->listFetch_s += 4;
- /* description starts at pkey->listFetch_s */
- pkey->listFetch_s += descr_len;
- lang_len = _libssh2_ntohu32(pkey->listFetch_s);
- pkey->listFetch_s += 4;
- /* lang starts at pkey->listFetch_s */
- pkey->listFetch_s += lang_len;
-
- if (pkey->listFetch_s >
- pkey->listFetch_data + pkey->listFetch_data_len) {
+ if (4*2 > end - pkey->listFetch_s)
+ pkey->listFetch_s = NULL;
+ else {
+ status = _libssh2_ntohu32(pkey->listFetch_s);
+ pkey->listFetch_s += 4;
+ descr_len = _libssh2_ntohu32(pkey->listFetch_s);
+ pkey->listFetch_s += 4;
+ if (descr_len > (size_t)(end - pkey->listFetch_s))
+ pkey->listFetch_s = NULL;
+ else {
+ /* description starts at pkey->listFetch_s */
+ pkey->listFetch_s += descr_len;
+ if (4 > end - pkey->listFetch_s)
+ pkey->listFetch_s = NULL;
+ else {
+ lang_len = _libssh2_ntohu32(pkey->listFetch_s);
+ pkey->listFetch_s += 4;
+ if (lang_len > (size_t)(end - pkey->listFetch_s))
+ pkey->listFetch_s = NULL;
+ else {
+ /* lang starts at pkey->listFetch_s */
+ pkey->listFetch_s += lang_len;
+ }
+ }
+ }
+ }
+
+ if (pkey->listFetch_s == NULL) {
_libssh2_error(session, LIBSSH2_ERROR_PUBLICKEY_PROTOCOL,
"Malformed publickey subsystem packet");
goto err_exit;
@@ -887,8 +922,12 @@ libssh2_publickey_list_fetch(LIBSSH2_PUBLICKEY * pkey, unsigned long *num_keys,
if (pkey->version == 1) {
unsigned long comment_len;
+ if (4 > end - pkey->listFetch_s)
+ goto err_exit;
comment_len = _libssh2_ntohu32(pkey->listFetch_s);
pkey->listFetch_s += 4;
+ if (comment_len > (size_t)(end - pkey->listFetch_s))
+ goto err_exit;
if (comment_len) {
list[keys].num_attrs = 1;
list[keys].attrs =
@@ -911,24 +950,42 @@ libssh2_publickey_list_fetch(LIBSSH2_PUBLICKEY * pkey, unsigned long *num_keys,
list[keys].num_attrs = 0;
list[keys].attrs = NULL;
}
+ if (4 > end - pkey->listFetch_s)
+ goto err_exit;
list[keys].name_len = _libssh2_ntohu32(pkey->listFetch_s);
pkey->listFetch_s += 4;
+ if (list[keys].name_len > (size_t)(end - pkey->listFetch_s))
+ goto err_exit;
list[keys].name = pkey->listFetch_s;
pkey->listFetch_s += list[keys].name_len;
+ if (4 > end - pkey->listFetch_s)
+ goto err_exit;
list[keys].blob_len = _libssh2_ntohu32(pkey->listFetch_s);
pkey->listFetch_s += 4;
+ if (list[keys].blob_len > (size_t)(end - pkey->listFetch_s))
+ goto err_exit;
list[keys].blob = pkey->listFetch_s;
pkey->listFetch_s += list[keys].blob_len;
} else {
/* Version == 2 */
+ if (4 > end - pkey->listFetch_s)
+ goto err_exit;
list[keys].name_len = _libssh2_ntohu32(pkey->listFetch_s);
pkey->listFetch_s += 4;
+ if (list[keys].name_len > (size_t)(end - pkey->listFetch_s))
+ goto err_exit;
list[keys].name = pkey->listFetch_s;
pkey->listFetch_s += list[keys].name_len;
+ if (4 > end - pkey->listFetch_s)
+ goto err_exit;
list[keys].blob_len = _libssh2_ntohu32(pkey->listFetch_s);
pkey->listFetch_s += 4;
+ if (list[keys].blob_len > (size_t)(end - pkey->listFetch_s))
+ goto err_exit;
list[keys].blob = pkey->listFetch_s;
pkey->listFetch_s += list[keys].blob_len;
+ if (4 > end - pkey->listFetch_s)
+ goto err_exit;
list[keys].num_attrs = _libssh2_ntohu32(pkey->listFetch_s);
pkey->listFetch_s += 4;
if (list[keys].num_attrs) {
@@ -943,14 +1000,22 @@ libssh2_publickey_list_fetch(LIBSSH2_PUBLICKEY * pkey, unsigned long *num_keys,
goto err_exit;
}
for(i = 0; i < list[keys].num_attrs; i++) {
+ if (4 > end - pkey->listFetch_s)
+ goto err_exit;
list[keys].attrs[i].name_len =
_libssh2_ntohu32(pkey->listFetch_s);
pkey->listFetch_s += 4;
+ if (list[keys].attrs[i].name_len > (size_t)(end - pkey->listFetch_s))
+ goto err_exit;
list[keys].attrs[i].name = (char *) pkey->listFetch_s;
pkey->listFetch_s += list[keys].attrs[i].name_len;
+ if (4 > end - pkey->listFetch_s)
+ goto err_exit;
list[keys].attrs[i].value_len =
_libssh2_ntohu32(pkey->listFetch_s);
pkey->listFetch_s += 4;
+ if (list[keys].attrs[i].value_len > (size_t)(end - pkey->listFetch_s))
+ goto err_exit;
list[keys].attrs[i].value = (char *) pkey->listFetch_s;
pkey->listFetch_s += list[keys].attrs[i].value_len;
diff --git a/src/session.c b/src/session.c
index 06e61dd..ba1bad5 100644
--- a/src/session.c
+++ b/src/session.c
@@ -763,6 +763,7 @@ session_startup(LIBSSH2_SESSION *session, libssh2_socket_t sock)
return rc;
session->startup_service_length =
+ (5 > session->startup_data_len) ? 0 :
_libssh2_ntohu32(session->startup_data + 1);
if ((session->startup_service_length != (sizeof("ssh-userauth") - 1))
@@ -1410,6 +1411,7 @@ libssh2_poll_channel_read(LIBSSH2_CHANNEL *channel, int extended)
packet = _libssh2_list_first(&session->packets);
while (packet) {
+ /* XXX assert(packet->data_len >= 5) XXX */
if ( channel->local.id == _libssh2_ntohu32(packet->data + 1)) {
if ( extended == 1 &&
(packet->data[0] == SSH_MSG_CHANNEL_EXTENDED_DATA
diff --git a/src/sftp.c b/src/sftp.c
index c142713..ad38638 100644
--- a/src/sftp.c
+++ b/src/sftp.c
@@ -249,6 +249,7 @@ sftp_packet_add(LIBSSH2_SFTP *sftp, unsigned char *data,
"Out of sync with the world");
}
+ /* XXX ??? assert(data_len >= 5); XXX */
request_id = _libssh2_ntohu32(&data[1]);
_libssh2_debug(session, LIBSSH2_TRACE_SFTP, "Received packet id %d",
@@ -635,21 +636,25 @@ sftp_attr2bin(unsigned char *p, const LIBSSH2_SFTP_ATTRIBUTES * attrs)
/* sftp_bin2attr
*/
-static int
-sftp_bin2attr(LIBSSH2_SFTP_ATTRIBUTES * attrs, const unsigned char *p)
+static const unsigned char *
+sftp_bin2attr(LIBSSH2_SFTP_ATTRIBUTES * attrs, const unsigned char *s, const unsigned char *end)
{
- const unsigned char *s = p;
-
memset(attrs, 0, sizeof(LIBSSH2_SFTP_ATTRIBUTES));
+ if (4 < end - p)
+ return NULL;
attrs->flags = _libssh2_ntohu32(s);
s += 4;
if (attrs->flags & LIBSSH2_SFTP_ATTR_SIZE) {
+ if (8 < end - p)
+ return NULL;
attrs->filesize = _libssh2_ntohu64(s);
s += 8;
}
if (attrs->flags & LIBSSH2_SFTP_ATTR_UIDGID) {
+ if (4*2 < end - p)
+ return NULL;
attrs->uid = _libssh2_ntohu32(s);
s += 4;
attrs->gid = _libssh2_ntohu32(s);
@@ -657,18 +662,22 @@ sftp_bin2attr(LIBSSH2_SFTP_ATTRIBUTES * attrs, const unsigned char *p)
}
if (attrs->flags & LIBSSH2_SFTP_ATTR_PERMISSIONS) {
+ if (4 < end - p)
+ return NULL;
attrs->permissions = _libssh2_ntohu32(s);
s += 4;
}
if (attrs->flags & LIBSSH2_SFTP_ATTR_ACMODTIME) {
+ if (4*2 < end - p)
+ return NULL;
attrs->atime = _libssh2_ntohu32(s);
s += 4;
attrs->mtime = _libssh2_ntohu32(s);
s += 4;
}
- return (s - p);
+ return s;
}
/* ************
@@ -1698,7 +1707,7 @@ static ssize_t sftp_readdir(LIBSSH2_SFTP_HANDLE *handle, char *buffer,
if (attrs)
memset(attrs, 0, sizeof(LIBSSH2_SFTP_ATTRIBUTES));
- s += sftp_bin2attr(attrs ? attrs : &attrs_dummy, s);
+ s = sftp_bin2attr(attrs ? attrs : &attrs_dummy, s, handle->u.dir.names_end);
handle->u.dir.next_name = (char *) s;
end:
@@ -1789,6 +1798,7 @@ static ssize_t sftp_readdir(LIBSSH2_SFTP_HANDLE *handle, char *buffer,
handle->u.dir.names_left = num_names;
handle->u.dir.names_packet = data;
+ handle->u.dir.names_end = data + data_len;
handle->u.dir.next_name = (char *) data + 9;
/* use the name popping mechanism from the start of the function */
@@ -2252,7 +2262,7 @@ static int sftp_fstat(LIBSSH2_SFTP_HANDLE *handle,
}
}
- sftp_bin2attr(attrs, data + 5);
+ sftp_bin2attr(attrs, data + 5, data + data_len);
LIBSSH2_FREE(session, data);
return 0;
@@ -2559,6 +2569,7 @@ static int sftp_unlink(LIBSSH2_SFTP *sftp, const char *filename,
sftp->unlink_state = libssh2_NB_state_idle;
+ /* XXX ??? assert(data_len >= 5+4); XXX */
retcode = _libssh2_ntohu32(data + 5);
LIBSSH2_FREE(session, data);
@@ -2669,6 +2680,7 @@ static int sftp_rename(LIBSSH2_SFTP *sftp, const char *source_filename,
sftp->rename_state = libssh2_NB_state_idle;
+ /* XXX ??? assert(data_len >= 5+4); XXX */
retcode = _libssh2_ntohu32(data + 5);
LIBSSH2_FREE(session, data);
@@ -2793,6 +2805,7 @@ static int sftp_fstatvfs(LIBSSH2_SFTP_HANDLE *handle, LIBSSH2_SFTP_STATVFS *st)
"Error waiting for FXP EXTENDED REPLY");
}
+ /* XXX ??? assert(data_len >= 5+4); XXX */
if (data[0] == SSH_FXP_STATUS) {
int retcode = _libssh2_ntohu32(data + 5);
sftp->fstatvfs_state = libssh2_NB_state_idle;
@@ -2919,6 +2932,7 @@ static int sftp_statvfs(LIBSSH2_SFTP *sftp, const char *path,
"Error waiting for FXP EXTENDED REPLY");
}
+ /* XXX ??? assert(data_len >= 5+4); XXX */
if (data[0] == SSH_FXP_STATUS) {
int retcode = _libssh2_ntohu32(data + 5);
sftp->statvfs_state = libssh2_NB_state_idle;
@@ -3051,6 +3065,7 @@ static int sftp_mkdir(LIBSSH2_SFTP *sftp, const char *path,
sftp->mkdir_state = libssh2_NB_state_idle;
+ /* XXX ??? assert(data_len >= 5+4); XXX */
retcode = _libssh2_ntohu32(data + 5);
LIBSSH2_FREE(session, data);
@@ -3145,6 +3160,7 @@ static int sftp_rmdir(LIBSSH2_SFTP *sftp, const char *path,
sftp->rmdir_state = libssh2_NB_state_idle;
+ /* XXX ??? assert(data_len >= 5+4); XXX */
retcode = _libssh2_ntohu32(data + 5);
LIBSSH2_FREE(session, data);
@@ -3188,6 +3204,7 @@ static int sftp_stat(LIBSSH2_SFTP *sftp, const char *path,
((stat_type ==
LIBSSH2_SFTP_SETSTAT) ? sftp_attrsize(attrs->flags) : 0);
unsigned char *s, *data;
+ unsigned char *data_end;
static const unsigned char stat_responses[2] =
{ SSH_FXP_ATTRS, SSH_FXP_STATUS };
int rc;
@@ -3258,6 +3275,8 @@ static int sftp_stat(LIBSSH2_SFTP *sftp, const char *path,
sftp->stat_state = libssh2_NB_state_idle;
+ /* XXX ??? assert(data_len >= 5+4); XXX */
+
if (data[0] == SSH_FXP_STATUS) {
int retcode;
@@ -3273,7 +3292,7 @@ static int sftp_stat(LIBSSH2_SFTP *sftp, const char *path,
}
memset(attrs, 0, sizeof(LIBSSH2_SFTP_ATTRIBUTES));
- sftp_bin2attr(attrs, data + 5);
+ sftp_bin2attr(attrs, data + 5, data + data_len);
LIBSSH2_FREE(session, data);
return 0;
@@ -3389,6 +3408,8 @@ static int sftp_symlink(LIBSSH2_SFTP *sftp, const char *path,
sftp->symlink_state = libssh2_NB_state_idle;
+ /* XXX ??? assert(data_len >= 5+4); XXX */
+
if (data[0] == SSH_FXP_STATUS) {
int retcode;
@@ -3410,8 +3431,13 @@ static int sftp_symlink(LIBSSH2_SFTP *sftp, const char *path,
"no name entries");
}
+ /* XXX ??? assert(data_len >= 5+4*2); XXX */
+
/* this reads a u32 and stores it into a signed 32bit value */
link_len = _libssh2_ntohu32(data + 9);
+
+ /* XXX ??? assert(data_len-(5+4*2) >= link_len); XXX */
+
if (link_len < target_len) {
memcpy(target, data + 13, link_len);
target[link_len] = 0;
diff --git a/src/sftp.h b/src/sftp.h
index 2ed32ce..91fc0a7 100644
--- a/src/sftp.h
+++ b/src/sftp.h
@@ -122,6 +122,7 @@ struct _LIBSSH2_SFTP_HANDLE
uint32_t names_left;
void *names_packet;
char *next_name;
+ char *names_end;
} dir;
} u;
diff --git a/src/userauth.c b/src/userauth.c
index cdfa25e..c799a40 100644
--- a/src/userauth.c
+++ b/src/userauth.c
@@ -69,6 +69,7 @@ static char *userauth_list(LIBSSH2_SESSION *session, const char *username,
service(14)"ssh-connection" + method_len(4) = 27 */
unsigned long methods_len;
unsigned char *s;
+ unsigned char *end;
int rc;
if (session->userauth_list_state == libssh2_NB_state_idle) {
@@ -143,7 +144,18 @@ static char *userauth_list(LIBSSH2_SESSION *session, const char *username,
return NULL;
}
+ if (5 > session->userauth_list_data_len) {
+ /* XXX ??? XXX */
+userauth_packet_overrun:
+ LIBSSH2_FREE(session, session->userauth_list_data);
+ session->userauth_list_data = NULL;
+ session->userauth_list_state = libssh2_NB_state_idle;
+ return NULL;
+ }
methods_len = _libssh2_ntohu32(session->userauth_list_data + 1);
+ if (methods_len > session->userauth_list_data_len - 5) {
+ goto userauth_packet_overrun;
+ }
/* Do note that the memory areas overlap! */
memmove(session->userauth_list_data, session->userauth_list_data + 5,
@@ -1561,6 +1573,7 @@ userauth_keyboard_interactive(LIBSSH2_SESSION * session,
LIBSSH2_USERAUTH_KBDINT_RESPONSE_FUNC((*response_callback)))
{
unsigned char *s;
+ unsigned char *end;
int rc;
static const unsigned char reply_codes[4] = {
@@ -1685,10 +1698,15 @@ userauth_keyboard_interactive(LIBSSH2_SESSION * session,
/* server requested PAM-like conversation */
s = session->userauth_kybd_data + 1;
+ end = session->userauth_kybd_data + session->userauth_kybd_data_len;
/* string name (ISO-10646 UTF-8) */
+ if (4 > end - s)
+ goto cleanup; /* XXX ??? XXX */
session->userauth_kybd_auth_name_len = _libssh2_ntohu32(s);
s += 4;
+ if (session->userauth_kybd_auth_name_len > (size_t)(end - s))
+ goto cleanup; /* XXX ??? XXX */
if(session->userauth_kybd_auth_name_len) {
session->userauth_kybd_auth_name =
LIBSSH2_ALLOC(session,
@@ -1706,8 +1724,12 @@ userauth_keyboard_interactive(LIBSSH2_SESSION * session,
}
/* string instruction (ISO-10646 UTF-8) */
+ if (4 > end - s)
+ goto cleanup; /* XXX ??? XXX */
session->userauth_kybd_auth_instruction_len = _libssh2_ntohu32(s);
s += 4;
+ if (session->userauth_kybd_auth_instruction_len > (size_t)(end - s))
+ goto cleanup; /* XXX ??? XXX */
if(session->userauth_kybd_auth_instruction_len) {
session->userauth_kybd_auth_instruction =
LIBSSH2_ALLOC(session,
@@ -1725,13 +1747,19 @@ userauth_keyboard_interactive(LIBSSH2_SESSION * session,
}
/* string language tag (as defined in [RFC-3066]) */
+ if (4 > end - s)
+ goto cleanup; /* XXX ??? XXX */
language_tag_len = _libssh2_ntohu32(s);
s += 4;
+ if (language_tag_len > (size_t)(end - s))
+ goto cleanup; /* XXX ??? XXX */
/* ignoring this field as deprecated */
s += language_tag_len;
/* int num-prompts */
+ if (4 > end - s)
+ goto cleanup; /* XXX ??? XXX */
session->userauth_kybd_num_prompts = _libssh2_ntohu32(s);
s += 4;
@@ -1760,9 +1788,13 @@ userauth_keyboard_interactive(LIBSSH2_SESSION * session,
for(i = 0; i < session->userauth_kybd_num_prompts; i++) {
/* string prompt[1] (ISO-10646 UTF-8) */
+ if (4 > end - s)
+ goto cleanup; /* XXX ??? XXX */
session->userauth_kybd_prompts[i].length =
_libssh2_ntohu32(s);
s += 4;
+ if (session->userauth_kybd_prompts[i].length > (size_t)(end - s))
+ goto cleanup; /* XXX ??? XXX */
session->userauth_kybd_prompts[i].text =
LIBSSH2_CALLOC(session,
session->userauth_kybd_prompts[i].length);
_______________________________________________
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