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authorEric Dumazet <edumazet@google.com>2018-06-01 09:23:02 -0700
committerDavid S. Miller <davem@davemloft.net>2018-06-04 11:31:53 -0400
commiteb73190f4fbeedf762394e92d6a4ec9ace684c88 (patch)
tree0dab3433d14a8bc1695a9c9e9a2c787643806add /net/packet
parent76a45194e5392ef6642785a3aa083818bd8541dd (diff)
downloadlinux-stericsson-eb73190f4fbeedf762394e92d6a4ec9ace684c88.tar.gz
net/packet: refine check for priv area size
syzbot was able to trick af_packet again [1] Various commits tried to address the problem in the past, but failed to take into account V3 header size. [1] tpacket_rcv: packet too big, clamped from 72 to 4294967224. macoff=96 BUG: KASAN: use-after-free in prb_run_all_ft_ops net/packet/af_packet.c:1016 [inline] BUG: KASAN: use-after-free in prb_fill_curr_block.isra.59+0x4e5/0x5c0 net/packet/af_packet.c:1039 Write of size 2 at addr ffff8801cb62000e by task kworker/1:2/2106 CPU: 1 PID: 2106 Comm: kworker/1:2 Not tainted 4.17.0-rc7+ #77 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: ipv6_addrconf addrconf_dad_work Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1b9/0x294 lib/dump_stack.c:113 print_address_description+0x6c/0x20b mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412 __asan_report_store2_noabort+0x17/0x20 mm/kasan/report.c:436 prb_run_all_ft_ops net/packet/af_packet.c:1016 [inline] prb_fill_curr_block.isra.59+0x4e5/0x5c0 net/packet/af_packet.c:1039 __packet_lookup_frame_in_block net/packet/af_packet.c:1094 [inline] packet_current_rx_frame net/packet/af_packet.c:1117 [inline] tpacket_rcv+0x1866/0x3340 net/packet/af_packet.c:2282 dev_queue_xmit_nit+0x891/0xb90 net/core/dev.c:2018 xmit_one net/core/dev.c:3049 [inline] dev_hard_start_xmit+0x16b/0xc10 net/core/dev.c:3069 __dev_queue_xmit+0x2724/0x34c0 net/core/dev.c:3584 dev_queue_xmit+0x17/0x20 net/core/dev.c:3617 neigh_resolve_output+0x679/0xad0 net/core/neighbour.c:1358 neigh_output include/net/neighbour.h:482 [inline] ip6_finish_output2+0xc9c/0x2810 net/ipv6/ip6_output.c:120 ip6_finish_output+0x5fe/0xbc0 net/ipv6/ip6_output.c:154 NF_HOOK_COND include/linux/netfilter.h:277 [inline] ip6_output+0x227/0x9b0 net/ipv6/ip6_output.c:171 dst_output include/net/dst.h:444 [inline] NF_HOOK include/linux/netfilter.h:288 [inline] ndisc_send_skb+0x100d/0x1570 net/ipv6/ndisc.c:491 ndisc_send_ns+0x3c1/0x8d0 net/ipv6/ndisc.c:633 addrconf_dad_work+0xbef/0x1340 net/ipv6/addrconf.c:4033 process_one_work+0xc1e/0x1b50 kernel/workqueue.c:2145 worker_thread+0x1cc/0x1440 kernel/workqueue.c:2279 kthread+0x345/0x410 kernel/kthread.c:240 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412 The buggy address belongs to the page: page:ffffea00072d8800 count:0 mapcount:-127 mapping:0000000000000000 index:0xffff8801cb620e80 flags: 0x2fffc0000000000() raw: 02fffc0000000000 0000000000000000 ffff8801cb620e80 00000000ffffff80 raw: ffffea00072e3820 ffffea0007132d20 0000000000000002 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801cb61ff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff8801cb61ff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff8801cb620000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff8801cb620080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff8801cb620100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff Fixes: 2b6867c2ce76 ("net/packet: fix overflow in check for priv area size") Fixes: dc808110bb62 ("packet: handle too big packets for PACKET_V3") Fixes: f6fb8f100b80 ("af-packet: TPACKET_V3 flexible buffer implementation.") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/packet')
-rw-r--r--net/packet/af_packet.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index b00aa959727d..082f981795f5 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -4250,7 +4250,7 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u,
goto out;
if (po->tp_version >= TPACKET_V3 &&
req->tp_block_size <=
- BLK_PLUS_PRIV((u64)req_u->req3.tp_sizeof_priv))
+ BLK_PLUS_PRIV((u64)req_u->req3.tp_sizeof_priv) + sizeof(struct tpacket3_hdr))
goto out;
if (unlikely(req->tp_frame_size < po->tp_hdrlen +
po->tp_reserve))