KASAN: use-after-free Read in tipc_sk_filter_rcv

From: syzbot
Date: Wed Mar 20 2019 - 17:22:09 EST

Hello,

syzbot found the following crash on:

HEAD commit: a0cfa79f ibmveth: Make array ibmveth_stats static
git tree: bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=154bec17200000
kernel config: https://syzkaller.appspot.com/x/.config?x=f05902bca21d8935
dashboard link: https://syzkaller.appspot.com/bug?extid=e863893591cc7a622e40
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=160f4c17200000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12c2ea6d200000

The bug was bisected to:

commit c55c8edafa91139419ed011f7d036274ce96be0b
Author: Hoang Le <hoang.h.le@xxxxxxxxxxxxxx>
Date: Tue Mar 19 11:49:50 2019 +0000

tipc: smooth change between replicast and broadcast

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=128c2007200000
final crash: https://syzkaller.appspot.com/x/report.txt?x=118c2007200000
console output: https://syzkaller.appspot.com/x/log.txt?x=168c2007200000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+e863893591cc7a622e40@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: c55c8eda ("tipc: smooth change between replicast and broadcast")

==================================================================
BUG: KASAN: use-after-free in tipc_sk_filter_rcv+0x2166/0x34f0 net/tipc/socket.c:2167
Read of size 4 at addr ffff88808ea58534 by task kworker/u4:0/7

CPU: 0 PID: 7 Comm: kworker/u4:0 Not tainted 5.0.0+ #61
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: tipc_send tipc_conn_send_work
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x172/0x1f0 lib/dump_stack.c:113
print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187
kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
__asan_report_load4_noabort+0x14/0x20 mm/kasan/generic_report.c:131
tipc_sk_filter_rcv+0x2166/0x34f0 net/tipc/socket.c:2167
tipc_sk_enqueue net/tipc/socket.c:2254 [inline]
tipc_sk_rcv+0xc45/0x25a0 net/tipc/socket.c:2305
tipc_topsrv_kern_evt+0x3b7/0x580 net/tipc/topsrv.c:610
tipc_conn_send_to_sock+0x43e/0x5f0 net/tipc/topsrv.c:283
tipc_conn_send_work+0x65/0x80 net/tipc/topsrv.c:303
process_one_work+0x98e/0x1790 kernel/workqueue.c:2269
worker_thread+0x98/0xe40 kernel/workqueue.c:2415
kthread+0x357/0x430 kernel/kthread.c:253
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Allocated by task 7:
save_stack+0x45/0xd0 mm/kasan/common.c:75
set_track mm/kasan/common.c:87 [inline]
__kasan_kmalloc mm/kasan/common.c:497 [inline]
__kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:470
kasan_kmalloc+0x9/0x10 mm/kasan/common.c:511
__do_kmalloc_node mm/slab.c:3686 [inline]
__kmalloc_node_track_caller+0x4e/0x70 mm/slab.c:3700
__kmalloc_reserve.isra.0+0x40/0xf0 net/core/skbuff.c:140
__alloc_skb+0x10b/0x5e0 net/core/skbuff.c:208
alloc_skb_fclone include/linux/skbuff.h:1107 [inline]
tipc_buf_acquire+0x2f/0x100 net/tipc/msg.c:66
tipc_msg_create+0x38/0x270 net/tipc/msg.c:98
tipc_topsrv_kern_evt+0x2a7/0x580 net/tipc/topsrv.c:602
tipc_conn_send_to_sock+0x43e/0x5f0 net/tipc/topsrv.c:283
tipc_conn_send_work+0x65/0x80 net/tipc/topsrv.c:303
process_one_work+0x98e/0x1790 kernel/workqueue.c:2269
worker_thread+0x98/0xe40 kernel/workqueue.c:2415
kthread+0x357/0x430 kernel/kthread.c:253
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Freed by task 7:
save_stack+0x45/0xd0 mm/kasan/common.c:75
set_track mm/kasan/common.c:87 [inline]
__kasan_slab_free+0x102/0x150 mm/kasan/common.c:459
kasan_slab_free+0xe/0x10 mm/kasan/common.c:467
__cache_free mm/slab.c:3498 [inline]
kfree+0xcf/0x230 mm/slab.c:3821
skb_free_head+0x93/0xb0 net/core/skbuff.c:557
skb_release_data+0x576/0x7a0 net/core/skbuff.c:577
skb_release_all+0x4d/0x60 net/core/skbuff.c:631
__kfree_skb net/core/skbuff.c:645 [inline]
kfree_skb net/core/skbuff.c:663 [inline]
kfree_skb+0xe8/0x390 net/core/skbuff.c:657
tipc_sk_proto_rcv net/tipc/socket.c:2009 [inline]
tipc_sk_filter_rcv+0x1e6a/0x34f0 net/tipc/socket.c:2162
tipc_sk_enqueue net/tipc/socket.c:2254 [inline]
tipc_sk_rcv+0xc45/0x25a0 net/tipc/socket.c:2305
tipc_topsrv_kern_evt+0x3b7/0x580 net/tipc/topsrv.c:610
tipc_conn_send_to_sock+0x43e/0x5f0 net/tipc/topsrv.c:283
tipc_conn_send_work+0x65/0x80 net/tipc/topsrv.c:303
process_one_work+0x98e/0x1790 kernel/workqueue.c:2269
worker_thread+0x98/0xe40 kernel/workqueue.c:2415
kthread+0x357/0x430 kernel/kthread.c:253
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

The buggy address belongs to the object at ffff88808ea58480
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 180 bytes inside of
1024-byte region [ffff88808ea58480, ffff88808ea58880)
The buggy address belongs to the page:
page:ffffea00023a9600 count:1 mapcount:0 mapping:ffff88812c3f0ac0 index:0x0 compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea00021bbd88 ffffea00023db488 ffff88812c3f0ac0
raw: 0000000000000000 ffff88808ea58000 0000000100000007 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88808ea58400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88808ea58480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88808ea58500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88808ea58580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88808ea58600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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