qemu_migration_cookie: Properly fetch cert DN

If 1024 was not enough to fit the DN, gnutls_x509_crt_get_dn would store
the required size in subjectlen. And since we're not checking the return
value of this function, we would happily overwrite some random memory.

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
This commit is contained in:
Jiri Denemark 2022-02-10 16:16:48 +01:00
parent d116f187c6
commit 3a311593e5

View File

@ -180,12 +180,12 @@ static char *
qemuDomainExtractTLSSubject(const char *certdir)
{
g_autofree char *certfile = NULL;
char *subject = NULL;
g_autofree char *subject = NULL;
g_autofree char *pemdata = NULL;
gnutls_datum_t pemdatum;
gnutls_x509_crt_t cert;
int rc;
size_t subjectlen;
size_t subjectlen = 256;
certfile = g_strdup_printf("%s/server-cert.pem", certdir);
@ -214,13 +214,21 @@ qemuDomainExtractTLSSubject(const char *certdir)
return NULL;
}
subjectlen = 1024;
subject = g_new0(char, subjectlen + 1);
gnutls_x509_crt_get_dn(cert, subject, &subjectlen);
rc = gnutls_x509_crt_get_dn(cert, subject, &subjectlen);
if (rc == GNUTLS_E_SHORT_MEMORY_BUFFER) {
subject = g_realloc(subject, subjectlen + 1);
rc = gnutls_x509_crt_get_dn(cert, subject, &subjectlen);
}
if (rc != 0) {
virReportError(VIR_ERR_INTERNAL_ERROR,
_("cannot get cert distinguished name: %s"),
gnutls_strerror(rc));
return NULL;
}
subject[subjectlen] = '\0';
return subject;
return g_steal_pointer(&subject);
}