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| author | Willem de Bruijn <willemb@google.com> | 2017-02-03 18:20:48 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-02-18 15:11:42 +0100 |
| commit | 26989c9d9904e3626443336bcefab0b6e7077d99 (patch) | |
| tree | abe0693a4f8c0a3c74bce7eda6b772601fe5a3cd | |
| parent | 0f895f51a831d73ce24158534784aba5b2a72a9e (diff) | |
| download | linux-rpi3-26989c9d9904e3626443336bcefab0b6e7077d99.tar.gz linux-rpi3-26989c9d9904e3626443336bcefab0b6e7077d99.tar.bz2 linux-rpi3-26989c9d9904e3626443336bcefab0b6e7077d99.zip | |
tun: read vnet_hdr_sz once
[ Upstream commit e1edab87faf6ca30cd137e0795bc73aa9a9a22ec ]
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).
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -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 18402d79539e..b31aca8146bb 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1187,9 +1187,11 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, } if (tun->flags & IFF_VNET_HDR) { - if (len < tun->vnet_hdr_sz) + int vnet_hdr_sz = READ_ONCE(tun->vnet_hdr_sz); + + if (len < vnet_hdr_sz) return -EINVAL; - len -= tun->vnet_hdr_sz; + len -= vnet_hdr_sz; n = copy_from_iter(&gso, sizeof(gso), from); if (n != sizeof(gso)) @@ -1201,7 +1203,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, if (tun16_to_cpu(tun, gso.hdr_len) > len) return -EINVAL; - iov_iter_advance(from, tun->vnet_hdr_sz - sizeof(gso)); + iov_iter_advance(from, vnet_hdr_sz - sizeof(gso)); } if ((tun->flags & TUN_TYPE_MASK) == IFF_TAP) { @@ -1348,7 +1350,7 @@ static ssize_t tun_put_user(struct tun_struct *tun, vlan_hlen = VLAN_HLEN; if (tun->flags & IFF_VNET_HDR) - vnet_hdr_sz = tun->vnet_hdr_sz; + vnet_hdr_sz = READ_ONCE(tun->vnet_hdr_sz); total = skb->len + vlan_hlen + vnet_hdr_sz; |