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mirror of https://git.tartarus.org/simon/putty.git synced 2025-07-12 16:47:42 -05:00

Tighten up a lot of casts from unsigned to int which are read by one

of the GET_32BIT macros and then used as length fields. Missing bounds
checks against zero have been added, and also I've introduced a helper
function toint() which casts from unsigned to int in such a way as to
avoid C undefined behaviour, since I'm not sure I trust compilers any
more to do the obviously sensible thing.

[originally from svn r9918]
This commit is contained in:
Simon Tatham
2013-07-14 10:45:54 +00:00
parent 1662a2f6cf
commit 896bb7c74d
11 changed files with 185 additions and 70 deletions

View File

@ -289,7 +289,7 @@ static int ssh2_read_mpint(void *data, int len, struct mpint_pos *ret)
if (len < 4)
goto error;
bytes = GET_32BIT(d);
bytes = toint(GET_32BIT(d));
if (bytes < 0 || len-4 < bytes)
goto error;
@ -745,6 +745,10 @@ int openssh_write(const Filename *filename, struct ssh2_userkey *key,
struct mpint_pos n, e, d, p, q, iqmp, dmp1, dmq1;
Bignum bd, bp, bq, bdmp1, bdmq1;
/*
* These blobs were generated from inside PuTTY, so we needn't
* treat them as untrusted.
*/
pos = 4 + GET_32BIT(pubblob);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n);
@ -798,6 +802,10 @@ int openssh_write(const Filename *filename, struct ssh2_userkey *key,
int pos;
struct mpint_pos p, q, g, y, x;
/*
* These blobs were generated from inside PuTTY, so we needn't
* treat them as untrusted.
*/
pos = 4 + GET_32BIT(pubblob);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q);
@ -1216,11 +1224,12 @@ int sshcom_encrypted(const Filename *filename, char **comment)
pos = 8;
if (key->keyblob_len < pos+4)
goto done; /* key is far too short */
pos += 4 + GET_32BIT(key->keyblob + pos); /* skip key type */
if (key->keyblob_len < pos+4)
len = toint(GET_32BIT(key->keyblob + pos));
if (len < 0 || len > key->keyblob_len - pos - 4)
goto done; /* key is far too short */
len = GET_32BIT(key->keyblob + pos); /* find cipher-type length */
if (key->keyblob_len < pos+4+len)
pos += 4 + len; /* skip key type */
len = toint(GET_32BIT(key->keyblob + pos)); /* find cipher-type length */
if (len < 0 || len > key->keyblob_len - pos - 4)
goto done; /* cipher type string is incomplete */
if (len != 4 || 0 != memcmp(key->keyblob + pos + 4, "none", 4))
answer = 1;
@ -1236,8 +1245,7 @@ int sshcom_encrypted(const Filename *filename, char **comment)
static int sshcom_read_mpint(void *data, int len, struct mpint_pos *ret)
{
int bits;
int bytes;
unsigned bits, bytes;
unsigned char *d = (unsigned char *) data;
if (len < 4)
@ -1309,7 +1317,8 @@ struct ssh2_userkey *sshcom_read(const Filename *filename, char *passphrase,
*/
pos = 8;
if (key->keyblob_len < pos+4 ||
(len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) {
(len = toint(GET_32BIT(key->keyblob + pos))) < 0 ||
len > key->keyblob_len - pos - 4) {
errmsg = "key blob does not contain a key type string";
goto error;
}
@ -1329,7 +1338,8 @@ struct ssh2_userkey *sshcom_read(const Filename *filename, char *passphrase,
* Determine the cipher type.
*/
if (key->keyblob_len < pos+4 ||
(len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) {
(len = toint(GET_32BIT(key->keyblob + pos))) < 0 ||
len > key->keyblob_len - pos - 4) {
errmsg = "key blob does not contain a cipher type string";
goto error;
}
@ -1347,7 +1357,8 @@ struct ssh2_userkey *sshcom_read(const Filename *filename, char *passphrase,
* Get hold of the encrypted part of the key.
*/
if (key->keyblob_len < pos+4 ||
(len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) {
(len = toint(GET_32BIT(key->keyblob + pos))) < 0 ||
len > key->keyblob_len - pos - 4) {
errmsg = "key blob does not contain actual key data";
goto error;
}
@ -1411,7 +1422,7 @@ struct ssh2_userkey *sshcom_read(const Filename *filename, char *passphrase,
/*
* Strip away the containing string to get to the real meat.
*/
len = GET_32BIT(ciphertext);
len = toint(GET_32BIT(ciphertext));
if (len < 0 || len > cipherlen-4) {
errmsg = "containing string was ill-formed";
goto error;
@ -1540,6 +1551,10 @@ int sshcom_write(const Filename *filename, struct ssh2_userkey *key,
int pos;
struct mpint_pos n, e, d, p, q, iqmp;
/*
* These blobs were generated from inside PuTTY, so we needn't
* treat them as untrusted.
*/
pos = 4 + GET_32BIT(pubblob);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n);
@ -1565,6 +1580,10 @@ int sshcom_write(const Filename *filename, struct ssh2_userkey *key,
int pos;
struct mpint_pos p, q, g, y, x;
/*
* These blobs were generated from inside PuTTY, so we needn't
* treat them as untrusted.
*/
pos = 4 + GET_32BIT(pubblob);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p);
pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q);