KASAN: use-after-free Read in rtnl_fill_ifinfo

From: syzbot
Date: Wed Sep 26 2018 - 12:16:08 EST

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Hello,

syzbot found the following crash on:

HEAD commit: 4b1bd6976945 net: phy: marvell: Fix build.
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1477df9e400000
kernel config: https://syzkaller.appspot.com/x/.config?x=443816db871edd66
dashboard link: https://syzkaller.appspot.com/bug?extid=1e0c7db78acf0d004daf
compiler: gcc (GCC) 8.0.1 20180413 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+1e0c7db78acf0d004daf@xxxxxxxxxxxxxxxxxxxxxxxxx

llcp: llcp_sock_recvmsg: Recv datagram failed state 5 -107 0
==================================================================
BUG: KASAN: use-after-free in rtnl_fill_ifinfo+0x420e/0x4670 net/core/rtnetlink.c:1630
Read of size 8 at addr ffff8801c2e7a4d8 by task syz-executor2/9379

CPU: 1 PID: 9379 Comm: syz-executor2 Not tainted 4.19.0-rc5+ #232
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+0x1c4/0x2b4 lib/dump_stack.c:113
print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256
kasan_report_error mm/kasan/report.c:354 [inline]
kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412
__asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
rtnl_fill_ifinfo+0x420e/0x4670 net/core/rtnetlink.c:1630
rtnl_dump_ifinfo+0x90a/0x1130 net/core/rtnetlink.c:1943
netlink_dump+0x519/0xd50 net/netlink/af_netlink.c:2226
netlink_recvmsg+0xf6f/0x1480 net/netlink/af_netlink.c:1984
sock_recvmsg_nosec+0x8c/0xb0 net/socket.c:794
___sys_recvmsg+0x2b6/0x680 net/socket.c:2278
__sys_recvmmsg+0x303/0xb90 net/socket.c:2390
do_sys_recvmmsg+0xec/0x1a0 net/socket.c:2471
__do_sys_recvmmsg net/socket.c:2484 [inline]
__se_sys_recvmmsg net/socket.c:2480 [inline]
__x64_sys_recvmmsg+0xbe/0x150 net/socket.c:2480
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457579
Code: 1d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 eb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f3e5c58cc78 EFLAGS: 00000246
ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000457579
RDX: 04000000000000f6 RSI: 00000000200037c0 RDI: 0000000000000003
RBP: 000000000072bfa0 R08: 0000000020003700 R09: 0000000000000000
R10: 0000000000000006 R11: 0000000000000246 R12: 00007f3e5c58d6d4
R13: 00000000004c3258 R14: 00000000004d4de8 R15: 00000000ffffffff

Allocated by task 5629:
save_stack+0x43/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
__do_kmalloc_node mm/slab.c:3682 [inline]
__kmalloc_node+0x47/0x70 mm/slab.c:3689
kmalloc_node include/linux/slab.h:555 [inline]
kzalloc_node include/linux/slab.h:718 [inline]
qdisc_alloc+0x10f/0xb50 net/sched/sch_generic.c:820
qdisc_create_dflt+0x7a/0x1e0 net/sched/sch_generic.c:894
attach_one_default_qdisc net/sched/sch_generic.c:1041 [inline]
netdev_for_each_tx_queue include/linux/netdevice.h:2114 [inline]
attach_default_qdiscs net/sched/sch_generic.c:1060 [inline]
dev_activate+0x82f/0xcb0 net/sched/sch_generic.c:1103
__dev_open+0x2cb/0x410 net/core/dev.c:1400
dev_open+0xf2/0x1b0 net/core/dev.c:1426
bond_enslave+0xfca/0x5f90 drivers/net/bonding/bond_main.c:1531
do_set_master+0x1c9/0x220 net/core/rtnetlink.c:2313
do_setlink+0xbe6/0x3f20 net/core/rtnetlink.c:2447
rtnl_newlink+0x136f/0x1d40 net/core/rtnetlink.c:3054
rtnetlink_rcv_msg+0x46a/0xc20 net/core/rtnetlink.c:4730
netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2447
rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:4748
netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
netlink_unicast+0x5a5/0x760 net/netlink/af_netlink.c:1336
netlink_sendmsg+0xa18/0xfc0 net/netlink/af_netlink.c:1901
sock_sendmsg_nosec net/socket.c:621 [inline]
sock_sendmsg+0xd5/0x120 net/socket.c:631
___sys_sendmsg+0x7fd/0x930 net/socket.c:2116
__sys_sendmsg+0x11d/0x280 net/socket.c:2154
__do_sys_sendmsg net/socket.c:2163 [inline]
__se_sys_sendmsg net/socket.c:2161 [inline]
__x64_sys_sendmsg+0x78/0xb0 net/socket.c:2161
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 5520:
save_stack+0x43/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
__kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
__cache_free mm/slab.c:3498 [inline]
kfree+0xcf/0x230 mm/slab.c:3813
qdisc_free+0x89/0x100 net/sched/sch_generic.c:941
qdisc_free_cb+0x19/0x20 net/sched/sch_generic.c:948
__rcu_reclaim kernel/rcu/rcu.h:236 [inline]
rcu_do_batch kernel/rcu/tree.c:2576 [inline]
invoke_rcu_callbacks kernel/rcu/tree.c:2880 [inline]
__rcu_process_callbacks kernel/rcu/tree.c:2847 [inline]
rcu_process_callbacks+0xf23/0x2670 kernel/rcu/tree.c:2864
__do_softirq+0x30b/0xad8 kernel/softirq.c:292

The buggy address belongs to the object at ffff8801c2e7a4c0
which belongs to the cache kmalloc-1024 of size 1024
The buggy address is located 24 bytes inside of
1024-byte region [ffff8801c2e7a4c0, ffff8801c2e7a8c0)
The buggy address belongs to the page:
page:ffffea00070b9e80 count:1 mapcount:0 mapping:ffff8801da800ac0 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffffea0007081708 ffffea00071f2688 ffff8801da800ac0
raw: 0000000000000000 ffff8801c2e7a040 0000000100000007 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8801c2e7a380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8801c2e7a400: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc

ffff8801c2e7a480: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb

^
ffff8801c2e7a500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8801c2e7a580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

---
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Next message: Borislav Petkov: "Re: [PATCH] Raise maximum number of memory controllers"
Previous message: Song Liu: "Re: [PATCH v3 bpf-next 03/10] bpf: introduce per-cpu cgroup local storage"
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