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Move null pointer checks to before FROMFIELD.

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This fixes an oversight in commit 0fc2d3b45: if a key creation
function returns a null 'ssh_key *', then adjusting the pointer's
address using FROMFIELD is a mistake, both in technical C terms
(undefined behaviour) and practically speaking because it will foil
the subsequent check against NULL. Instead, if we're going to check a
pointer against NULL, we must do it _before_ applying this kind of
address-adjusting type conversion.
This commit is contained in:
Simon Tatham
2018-05-31 18:32:09 +01:00
parent 2cf07bb8fe
commit 619f6722d8
3 changed files with 40 additions and 23 deletions
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24
sshrsa.c
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@ -601,11 +601,15 @@ static ssh_key *rsa2_createkey(const ssh_keyalg *self,
const void *pub_blob, int pub_len,
const void *priv_blob, int priv_len)
{
ssh_key *sshk;
struct RSAKey *rsa;
const char *pb = (const char *) priv_blob;
rsa = FROMFIELD(rsa2_newkey(self, pub_blob, pub_len),
struct RSAKey, sshk);
sshk = rsa2_newkey(self, pub_blob, pub_len);
if (!sshk)
return NULL;
rsa = FROMFIELD(sshk, struct RSAKey, sshk);
rsa->private_exponent = getmp(&pb, &priv_len);
rsa->p = getmp(&pb, &priv_len);
rsa->q = getmp(&pb, &priv_len);
@ -664,13 +668,15 @@ static void rsa2_openssh_fmtkey(ssh_key *key, BinarySink *bs)
static int rsa2_pubkey_bits(const ssh_keyalg *self,
const void *blob, int len)
{
ssh_key *sshk;
struct RSAKey *rsa;
int ret;
rsa = FROMFIELD(rsa2_newkey(self, blob, len),
struct RSAKey, sshk);
if (!rsa)
return -1;
sshk = rsa2_newkey(self, blob, len);
if (!sshk)
return -1;
rsa = FROMFIELD(sshk, struct RSAKey, sshk);
ret = bignum_bitcount(rsa->modulus);
rsa2_freekey(&rsa->sshk);
@ -818,8 +824,10 @@ const ssh_keyalg ssh_rsa = {
struct RSAKey *ssh_rsakex_newkey(const void *data, int len)
{
return FROMFIELD(rsa2_newkey(&ssh_rsa, data, len),
struct RSAKey, sshk);
ssh_key *sshk = rsa2_newkey(&ssh_rsa, data, len);
if (!sshk)
return NULL;
return FROMFIELD(sshk, struct RSAKey, sshk);
}
void ssh_rsakex_freekey(struct RSAKey *key)