Commit cca8ea3b authored by Phillip Potter's avatar Phillip Potter Committed by David S. Miller
Browse files

net: tun: set tun->dev->addr_len during TUNSETLINK processing 

When changing type with TUNSETLINK ioctl command, set tun->dev->addr_len
to match the appropriate type, using new tun_get_addr_len utility function
which returns appropriate address length for given type. Fixes a
KMSAN-found uninit-value bug reported by syzbot at:
https://syzkaller.appspot.com/bug?id=0766d38c656abeace60621896d705743aeefed51



Reported-by: default avatar <syzbot+001516d86dbe88862cec@syzkaller.appspotmail.com>
Diagnosed-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarPhillip Potter <phil@philpotter.co.uk>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 63cf3238

drivers/net/tun.c

+48 −0
Original line number Diff line number Diff line
@@ -69,6 +69,14 @@ 
#include <linux/bpf.h>

#include <linux/bpf_trace.h>

#include <linux/mutex.h>

#include <linux/ieee802154.h>

#include <linux/if_ltalk.h>

#include <uapi/linux/if_fddi.h>

#include <uapi/linux/if_hippi.h>

#include <uapi/linux/if_fc.h>

#include <net/ax25.h>

#include <net/rose.h>

#include <net/6lowpan.h>



#include <linux/uaccess.h>

#include <linux/proc_fs.h>
@@ -2919,6 +2927,45 @@ static int tun_set_ebpf(struct tun_struct *tun, struct tun_prog __rcu **prog_p, 
	return __tun_set_ebpf(tun, prog_p, prog);

}



/* Return correct value for tun->dev->addr_len based on tun->dev->type. */

static unsigned char tun_get_addr_len(unsigned short type)

{

	switch (type) {

	case ARPHRD_IP6GRE:

	case ARPHRD_TUNNEL6:

		return sizeof(struct in6_addr);

	case ARPHRD_IPGRE:

	case ARPHRD_TUNNEL:

	case ARPHRD_SIT:

		return 4;

	case ARPHRD_ETHER:

		return ETH_ALEN;

	case ARPHRD_IEEE802154:

	case ARPHRD_IEEE802154_MONITOR:

		return IEEE802154_EXTENDED_ADDR_LEN;

	case ARPHRD_PHONET_PIPE:

	case ARPHRD_PPP:

	case ARPHRD_NONE:

		return 0;

	case ARPHRD_6LOWPAN:

		return EUI64_ADDR_LEN;

	case ARPHRD_FDDI:

		return FDDI_K_ALEN;

	case ARPHRD_HIPPI:

		return HIPPI_ALEN;

	case ARPHRD_IEEE802:

		return FC_ALEN;

	case ARPHRD_ROSE:

		return ROSE_ADDR_LEN;

	case ARPHRD_NETROM:

		return AX25_ADDR_LEN;

	case ARPHRD_LOCALTLK:

		return LTALK_ALEN;

	default:

		return 0;

	}

}



static long __tun_chr_ioctl(struct file *file, unsigned int cmd,

			    unsigned long arg, int ifreq_len)

{
@@ -3082,6 +3129,7 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd, 
				break;

			}

			tun->dev->type = (int) arg;

			tun->dev->addr_len = tun_get_addr_len(tun->dev->type);

			netif_info(tun, drv, tun->dev, "linktype set to %d\n",

				   tun->dev->type);

			call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE,