4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet edumazet@google.com
[ Upstream commit 945d015ee0c3095d2290e845565a23dedfd8027c ]
We should put copy_skb in receive_queue only after a successful call to virtio_net_hdr_from_skb().
syzbot report :
BUG: KASAN: use-after-free in __skb_unlink include/linux/skbuff.h:1843 [inline] BUG: KASAN: use-after-free in __skb_dequeue include/linux/skbuff.h:1863 [inline] BUG: KASAN: use-after-free in skb_dequeue+0x16a/0x180 net/core/skbuff.c:2815 Read of size 8 at addr ffff8801b044ecc0 by task syz-executor217/4553
CPU: 0 PID: 4553 Comm: syz-executor217 Not tainted 4.18.0-rc1+ #111 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1c9/0x2b4 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_load8_noabort+0x14/0x20 mm/kasan/report.c:433 __skb_unlink include/linux/skbuff.h:1843 [inline] __skb_dequeue include/linux/skbuff.h:1863 [inline] skb_dequeue+0x16a/0x180 net/core/skbuff.c:2815 skb_queue_purge+0x26/0x40 net/core/skbuff.c:2852 packet_set_ring+0x675/0x1da0 net/packet/af_packet.c:4331 packet_release+0x630/0xd90 net/packet/af_packet.c:2991 __sock_release+0xd7/0x260 net/socket.c:603 sock_close+0x19/0x20 net/socket.c:1186 __fput+0x35b/0x8b0 fs/file_table.c:209 ____fput+0x15/0x20 fs/file_table.c:243 task_work_run+0x1ec/0x2a0 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x1b08/0x2750 kernel/exit.c:865 do_group_exit+0x177/0x440 kernel/exit.c:968 __do_sys_exit_group kernel/exit.c:979 [inline] __se_sys_exit_group kernel/exit.c:977 [inline] __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:977 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4448e9 Code: Bad RIP value. RSP: 002b:00007ffd5f777ca8 EFLAGS: 00000202 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004448e9 RDX: 00000000004448e9 RSI: 000000000000fcfb RDI: 0000000000000001 RBP: 00000000006cf018 R08: 00007ffd0000a45b R09: 0000000000000000 R10: 00007ffd5f777e48 R11: 0000000000000202 R12: 00000000004021f0 R13: 0000000000402280 R14: 0000000000000000 R15: 0000000000000000
Allocated by task 4553: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3554 skb_clone+0x1f5/0x500 net/core/skbuff.c:1282 tpacket_rcv+0x28f7/0x3200 net/packet/af_packet.c:2221 deliver_skb net/core/dev.c:1925 [inline] deliver_ptype_list_skb net/core/dev.c:1940 [inline] __netif_receive_skb_core+0x1bfb/0x3680 net/core/dev.c:4611 __netif_receive_skb+0x2c/0x1e0 net/core/dev.c:4693 netif_receive_skb_internal+0x12e/0x7d0 net/core/dev.c:4767 netif_receive_skb+0xbf/0x420 net/core/dev.c:4791 tun_rx_batched.isra.55+0x4ba/0x8c0 drivers/net/tun.c:1571 tun_get_user+0x2af1/0x42f0 drivers/net/tun.c:1981 tun_chr_write_iter+0xb9/0x154 drivers/net/tun.c:2009 call_write_iter include/linux/fs.h:1795 [inline] new_sync_write fs/read_write.c:474 [inline] __vfs_write+0x6c6/0x9f0 fs/read_write.c:487 vfs_write+0x1f8/0x560 fs/read_write.c:549 ksys_write+0x101/0x260 fs/read_write.c:598 __do_sys_write fs/read_write.c:610 [inline] __se_sys_write fs/read_write.c:607 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:607 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe
Freed by task 4553: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3498 [inline] kmem_cache_free+0x86/0x2d0 mm/slab.c:3756 kfree_skbmem+0x154/0x230 net/core/skbuff.c:582 __kfree_skb net/core/skbuff.c:642 [inline] kfree_skb+0x1a5/0x580 net/core/skbuff.c:659 tpacket_rcv+0x189e/0x3200 net/packet/af_packet.c:2385 deliver_skb net/core/dev.c:1925 [inline] deliver_ptype_list_skb net/core/dev.c:1940 [inline] __netif_receive_skb_core+0x1bfb/0x3680 net/core/dev.c:4611 __netif_receive_skb+0x2c/0x1e0 net/core/dev.c:4693 netif_receive_skb_internal+0x12e/0x7d0 net/core/dev.c:4767 netif_receive_skb+0xbf/0x420 net/core/dev.c:4791 tun_rx_batched.isra.55+0x4ba/0x8c0 drivers/net/tun.c:1571 tun_get_user+0x2af1/0x42f0 drivers/net/tun.c:1981 tun_chr_write_iter+0xb9/0x154 drivers/net/tun.c:2009 call_write_iter include/linux/fs.h:1795 [inline] new_sync_write fs/read_write.c:474 [inline] __vfs_write+0x6c6/0x9f0 fs/read_write.c:487 vfs_write+0x1f8/0x560 fs/read_write.c:549 ksys_write+0x101/0x260 fs/read_write.c:598 __do_sys_write fs/read_write.c:610 [inline] __se_sys_write fs/read_write.c:607 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:607 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe
The buggy address belongs to the object at ffff8801b044ecc0 which belongs to the cache skbuff_head_cache of size 232 The buggy address is located 0 bytes inside of 232-byte region [ffff8801b044ecc0, ffff8801b044eda8) The buggy address belongs to the page: page:ffffea0006c11380 count:1 mapcount:0 mapping:ffff8801d9be96c0 index:0x0 flags: 0x2fffc0000000100(slab) raw: 02fffc0000000100 ffffea0006c17988 ffff8801d9bec248 ffff8801d9be96c0 raw: 0000000000000000 ffff8801b044e040 000000010000000c 0000000000000000 page dumped because: kasan: bad access detected
Memory state around the buggy address: ffff8801b044eb80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff8801b044ec00: 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc
ffff8801b044ec80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
^ ffff8801b044ed00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801b044ed80: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc
Fixes: 58d19b19cd99 ("packet: vnet_hdr support for tpacket_rcv") Signed-off-by: Eric Dumazet edumazet@google.com Reported-by: syzbot syzkaller@googlegroups.com Cc: Willem de Bruijn willemb@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/packet/af_packet.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-)
--- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2265,6 +2265,12 @@ static int tpacket_rcv(struct sk_buff *s if (po->stats.stats1.tp_drops) status |= TP_STATUS_LOSING; } + + if (do_vnet && + __packet_rcv_vnet(skb, h.raw + macoff - + sizeof(struct virtio_net_hdr))) + goto drop_n_account; + po->stats.stats1.tp_packets++; if (copy_skb) { status |= TP_STATUS_COPY; @@ -2272,14 +2278,6 @@ static int tpacket_rcv(struct sk_buff *s } spin_unlock(&sk->sk_receive_queue.lock);
- if (do_vnet) { - if (__packet_rcv_vnet(skb, h.raw + macoff - - sizeof(struct virtio_net_hdr))) { - spin_lock(&sk->sk_receive_queue.lock); - goto drop_n_account; - } - } - skb_copy_bits(skb, 0, h.raw + macoff, snaplen);
if (!(ts_status = tpacket_get_timestamp(skb, &ts, po->tp_tstamp)))