This is a note to let you know that I've just added the patch titled net: tun: set tun->dev->addr_len during TUNSETLINK processing to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: net-tun-set-tun-dev-addr_len-during-tunsetlink-processing.patch and it can be found in the queue-4.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From cca8ea3b05c972ffb5295367e6c544369b45fbdd Mon Sep 17 00:00:00 2001 From: Phillip Potter <phil@xxxxxxxxxxxxxxxx> Date: Tue, 6 Apr 2021 18:45:54 +0100 Subject: net: tun: set tun->dev->addr_len during TUNSETLINK processing From: Phillip Potter <phil@xxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxxxxxxxxx Diagnosed-by: Eric Dumazet <edumazet@xxxxxxxxxx> Signed-off-by: Phillip Potter <phil@xxxxxxxxxxxxxxxx> Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/net/tun.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -75,6 +75,14 @@ #include <linux/skb_array.h> #include <linux/bpf.h> #include <linux/bpf_trace.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> @@ -2292,6 +2300,45 @@ unlock: return ret; } +/* 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) { @@ -2434,6 +2481,7 @@ static long __tun_chr_ioctl(struct file 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; Patches currently in stable-queue which might be from phil@xxxxxxxxxxxxxxxx are queue-4.14/net-tun-set-tun-dev-addr_len-during-tunsetlink-processing.patch