Hi,
Note that since we compile with CPPFLAGS="-D_FORTIFY_SOURCE=2" this
leads to at most an application crash, but as discussed with Mortiz I
increased the severity to RC, so it should be fixed for the Stretch
release.
I'm attaching the patch and a tenative reproducer case (as from SuSE).
But I noticed that a buffer overflow is still triggered somewhere. I
have not digged into it further so far.
Regards,
Salvatore
Description: CVE-2016-6318: Stack-based buffer overflow when parsing large GECOS field
It is not safe to pass words longer than STRINGSIZE further to cracklib
so the longbuffer cannot be longer than STRINGSIZE.
Origin: vendor, https://bugzilla.redhat.com/attachment.cgi?id=1188599
Bug-Debian: https://bugs.debian.org/834502
Bug-RedHat: https://bugzilla.redhat.com/show_bug.cgi?id=1364944
Forwarded: not-needed
Author: Salvatore Bonaccorso <[email protected]>
Last-Update: 2016-08-16
--- a/lib/fascist.c
+++ b/lib/fascist.c
@@ -502,7 +502,7 @@ FascistGecosUser(char *password, const c
char gbuffer[STRINGSIZE];
char tbuffer[STRINGSIZE];
char *uwords[STRINGSIZE];
- char longbuffer[STRINGSIZE * 2];
+ char longbuffer[STRINGSIZE];
if (gecos == NULL)
gecos = "";
@@ -583,38 +583,47 @@ FascistGecosUser(char *password, const c
{
for (i = 0; i < j; i++)
{
- strcpy(longbuffer, uwords[i]);
- strcat(longbuffer, uwords[j]);
-
- if (GTry(longbuffer, password))
+ if (strlen(uwords[i]) + strlen(uwords[j]) < STRINGSIZE)
{
- return _("it is derived from your password entry");
- }
-
- strcpy(longbuffer, uwords[j]);
- strcat(longbuffer, uwords[i]);
+ strcpy(longbuffer, uwords[i]);
+ strcat(longbuffer, uwords[j]);
- if (GTry(longbuffer, password))
- {
- return _("it's derived from your password entry");
+ if (GTry(longbuffer, password))
+ {
+ return _("it is derived from your password entry");
+ }
+
+ strcpy(longbuffer, uwords[j]);
+ strcat(longbuffer, uwords[i]);
+
+ if (GTry(longbuffer, password))
+ {
+ return _("it's derived from your password entry");
+ }
}
- longbuffer[0] = uwords[i][0];
- longbuffer[1] = '\0';
- strcat(longbuffer, uwords[j]);
-
- if (GTry(longbuffer, password))
+ if (strlen(uwords[j]) < STRINGSIZE - 1)
{
- return _("it is derivable from your password entry");
+ longbuffer[0] = uwords[i][0];
+ longbuffer[1] = '\0';
+ strcat(longbuffer, uwords[j]);
+
+ if (GTry(longbuffer, password))
+ {
+ return _("it is derivable from your password entry");
+ }
}
- longbuffer[0] = uwords[j][0];
- longbuffer[1] = '\0';
- strcat(longbuffer, uwords[i]);
-
- if (GTry(longbuffer, password))
+ if (strlen(uwords[i]) < STRINGSIZE - 1)
{
- return _("it's derivable from your password entry");
+ longbuffer[0] = uwords[j][0];
+ longbuffer[1] = '\0';
+ strcat(longbuffer, uwords[i]);
+
+ if (GTry(longbuffer, password))
+ {
+ return _("it's derivable from your password entry");
+ }
}
}
}
#include <stdlib.h>
#include <string.h>
#include <crack.h>
int main(int argc, char **argv) {
char *defaultdict = NULL;
defaultdict = strdup(GetDefaultCracklibDict());
FascistCheck("tux", defaultdict);
FascistCheckUser("foobar", defaultdict, "tux", "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA,BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB,CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC,DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD");
free(defaultdict);
}
