Date:   Thu, 09 Jul 2020 16:54:19 -0700
From:   syzbot <syzbot+20b90969babe05609947@...kaller.appspotmail.com>
To:     dledford@...hat.com, jgg@...pe.ca, linux-kernel@...r.kernel.org,
        linux-rdma@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: KASAN: use-after-free Read in netdevice_event_work_handler

Hello,

syzbot found the following crash on:

HEAD commit:    0bddd227 Documentation: update for gcc 4.9 requirement
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1418afb7100000
kernel config:  https://syzkaller.appspot.com/x/.config?x=66ad203c2bb6d8b
dashboard link: https://syzkaller.appspot.com/bug?extid=20b90969babe05609947
compiler:       gcc (GCC) 10.1.0-syz 20200507
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12a8edff100000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=167d3bb7100000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+20b90969babe05609947@...kaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in dev_put include/linux/netdevice.h:3853 [inline]
BUG: KASAN: use-after-free in netdevice_event_work_handler+0x15b/0x1b0 drivers/infiniband/core/roce_gid_mgmt.c:627
Read of size 8 at addr ffff88807b13e568 by task kworker/u4:0/7

CPU: 0 PID: 7 Comm: kworker/u4:0 Not tainted 5.8.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: gid-cache-wq netdevice_event_work_handler
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x18f/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xae/0x436 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 dev_put include/linux/netdevice.h:3853 [inline]
 netdevice_event_work_handler+0x15b/0x1b0 drivers/infiniband/core/roce_gid_mgmt.c:627
 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
 kthread+0x3b5/0x4a0 kernel/kthread.c:291
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293

Allocated by task 13061:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:494
 kmalloc_node include/linux/slab.h:578 [inline]
 kvmalloc_node+0x61/0xf0 mm/util.c:574
 kvmalloc include/linux/mm.h:753 [inline]
 kvzalloc include/linux/mm.h:761 [inline]
 alloc_netdev_mqs+0x97/0xdc0 net/core/dev.c:9938
 __ip_tunnel_create+0x201/0x580 net/ipv4/ip_tunnel.c:254
 ip_tunnel_init_net+0x32b/0x980 net/ipv4/ip_tunnel.c:1072
 ops_init+0xaf/0x470 net/core/net_namespace.c:151
 setup_net+0x2d8/0x850 net/core/net_namespace.c:341
 copy_net_ns+0x2cf/0x5e0 net/core/net_namespace.c:482
 create_new_namespaces+0x3f6/0xb10 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0xbd/0x1f0 kernel/nsproxy.c:231
 ksys_unshare+0x36c/0x9a0 kernel/fork.c:2983
 __do_sys_unshare kernel/fork.c:3051 [inline]
 __se_sys_unshare kernel/fork.c:3049 [inline]
 __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3049
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 13061:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 kasan_set_free_info mm/kasan/common.c:316 [inline]
 __kasan_slab_free+0xf5/0x140 mm/kasan/common.c:455
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x103/0x2c0 mm/slab.c:3757
 kvfree+0x42/0x50 mm/util.c:603
 device_release+0x71/0x200 drivers/base/core.c:1559
 kobject_cleanup lib/kobject.c:693 [inline]
 kobject_release lib/kobject.c:722 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x1c0/0x270 lib/kobject.c:739
 put_device+0x1b/0x30 drivers/base/core.c:2779
 free_netdev+0x35d/0x480 net/core/dev.c:10054
 __ip_tunnel_create+0x48f/0x580 net/ipv4/ip_tunnel.c:274
 ip_tunnel_init_net+0x32b/0x980 net/ipv4/ip_tunnel.c:1072
 ops_init+0xaf/0x470 net/core/net_namespace.c:151
 setup_net+0x2d8/0x850 net/core/net_namespace.c:341
 copy_net_ns+0x2cf/0x5e0 net/core/net_namespace.c:482
 create_new_namespaces+0x3f6/0xb10 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0xbd/0x1f0 kernel/nsproxy.c:231
 ksys_unshare+0x36c/0x9a0 kernel/fork.c:2983
 __do_sys_unshare kernel/fork.c:3051 [inline]
 __se_sys_unshare kernel/fork.c:3049 [inline]
 __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3049
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff88807b13e000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 1384 bytes inside of
 4096-byte region [ffff88807b13e000, ffff88807b13f000)
The buggy address belongs to the page:
page:ffffea0001ec4f80 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 head:ffffea0001ec4f80 order:1 compound_mapcount:0
flags: 0xfffe0000010200(slab|head)
raw: 00fffe0000010200 ffffea0001ecce88 ffffea0001987988 ffff8880aa002000
raw: 0000000000000000 ffff88807b13e000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88807b13e400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88807b13e480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88807b13e500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                          ^
 ffff88807b13e580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88807b13e600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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