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

commit cca8ea3b05c972ffb5295367e6c544369b45fbdd upstream.

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: syzbot+001516d86dbe88862cec@syzkaller.appspotmail.com
Diagnosed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Phillip Potter <phil@philpotter.co.uk>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Phillip Potter 2021-04-06 18:45:54 +01:00 committed by Greg Kroah-Hartman
parent ed13df88c6
commit 0a790ad135
1 changed files with 48 additions and 0 deletions
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48
drivers/net/tun.c
View File

@ -68,6 +68,14 @@
#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>
@ -3043,6 +3051,45 @@ static int tun_set_ebpf(struct tun_struct *tun, struct tun_prog **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)
{
@ -3198,6 +3245,7 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
ret = -EBUSY;
} else {
tun->dev->type = (int) arg;
tun->dev->addr_len = tun_get_addr_len(tun->dev->type);
tun_debug(KERN_INFO, tun, "linktype set to %d\n",
tun->dev->type);
ret = 0;