diff options
| author | Willem de Bruijn <willemb@google.com> | 2017-02-03 18:20:48 -0500 |
|---|---|---|
| committer | Mister Oyster <oysterized@gmail.com> | 2017-07-04 12:11:27 +0200 |
| commit | eb9da50e79c1e422d6b6176e6669072966a13068 (patch) | |
| tree | c92b9c6d08620ba2bdc01595819d5382dcd8c1a4 /drivers | |
| parent | 010679ee634b86e532db3302aa2085735f30aedf (diff) | |
tun: read vnet_hdr_sz once
commit e1edab87faf6ca30cd137e0795bc73aa9a9a22ec upstream.
When IFF_VNET_HDR is enabled, a virtio_net header must precede data.
Data length is verified to be greater than or equal to expected header
length tun->vnet_hdr_sz before copying.
Read this value once and cache locally, as it can be updated between
the test and use (TOCTOU).
[js] we have TUN_VNET_HDR in 3.12
Signed-off-by: Willem de Bruijn <willemb@google.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
CC: Eric Dumazet <edumazet@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
[wt: s/READ_ONCE/ACCESS_ONCE]
Signed-off-by: Willy Tarreau <w@1wt.eu>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/net/tun.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 21ec9ae89..d818f990c 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1087,9 +1087,11 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, } if (tun->flags & TUN_VNET_HDR) { - if (len < tun->vnet_hdr_sz) + int vnet_hdr_sz = ACCESS_ONCE(tun->vnet_hdr_sz); + + if (len < vnet_hdr_sz) return -EINVAL; - len -= tun->vnet_hdr_sz; + len -= vnet_hdr_sz; if (memcpy_fromiovecend((void *)&gso, iv, offset, sizeof(gso))) return -EFAULT; @@ -1100,7 +1102,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, if (gso.hdr_len > len) return -EINVAL; - offset += tun->vnet_hdr_sz; + offset += vnet_hdr_sz; } if ((tun->flags & TUN_TYPE_MASK) == TUN_TAP_DEV) { @@ -1275,7 +1277,7 @@ static ssize_t tun_put_user(struct tun_struct *tun, int vnet_hdr_sz = 0; if (tun->flags & TUN_VNET_HDR) - vnet_hdr_sz = tun->vnet_hdr_sz; + vnet_hdr_sz = ACCESS_ONCE(tun->vnet_hdr_sz); if (!(tun->flags & TUN_NO_PI)) { if ((len -= sizeof(pi)) < 0) |