From: Andrey Konovalov Date: Wed, 29 Mar 2017 14:11:20 +0000 (+0200) Subject: net/packet: fix overflow in check for priv area size X-Git-Tag: Ubuntu-snapdragon-4.4.0-1055.59~594 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=79beb34f69d31a2dbe59d34df4958cbd37b3c1fb;p=mirror_ubuntu-artful-kernel.git net/packet: fix overflow in check for priv area size Subtracting tp_sizeof_priv from tp_block_size and casting to int to check whether one is less then the other doesn't always work (both of them are unsigned ints). Compare them as is instead. Also cast tp_sizeof_priv to u64 before using BLK_PLUS_PRIV, as it can overflow inside BLK_PLUS_PRIV otherwise. Signed-off-by: Andrey Konovalov Acked-by: Eric Dumazet Signed-off-by: David S. Miller BugLink: https://bugs.launchpad.net/bugs/1678009 CVE-2017-7308 (cherry picked from commit 2b6867c2ce76c596676bec7d2d525af525fdc6e2 linux-net) Signed-off-by: Andy Whitcroft --- diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index f223d1c80ccf..937f26e9ba02 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -4115,8 +4115,8 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u, if (unlikely(!PAGE_ALIGNED(req->tp_block_size))) goto out; if (po->tp_version >= TPACKET_V3 && - (int)(req->tp_block_size - - BLK_PLUS_PRIV(req_u->req3.tp_sizeof_priv)) <= 0) + req->tp_block_size <= + BLK_PLUS_PRIV((u64)req_u->req3.tp_sizeof_priv)) goto out; if (unlikely(req->tp_frame_size < po->tp_hdrlen + po->tp_reserve))