Re: KASAN: use-after-free Read in mac80211_hwsim_del_radio

[Kirill Tkhai]

Hi,

01.03.2018, 11:46, "syzbot" <syzbot+70ce058e01259de7bb1d@xxxxxxxxxxxxxxxxxxxxxxxxx>:
> Hello,
>
> syzbot hit the following crash on upstream commit
> f3afe530d644488a074291da04a69a296ab63046 (Tue Feb 27 22:02:39 2018 +0000)
> Merge branch 'fixes-v4.16-rc4' of
> git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
>
> So far this crash happened 4 times on upstream.
> Unfortunately, I don't have any reproducer for this crash yet.
> Raw console output is attached.
> compiler: gcc (GCC) 7.1.1 20170620
> .config is attached.
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+70ce058e01259de7bb1d@xxxxxxxxxxxxxxxxxxxxxxxxx
> It will help syzbot understand when the bug is fixed. See footer for
> details.
> If you forward the report, please keep this part and the footer.
>
> ==================================================================
> BUG: KASAN: use-after-free in strlen+0x85/0xa0 lib/string.c:482
> Read of size 1 at addr ffff8801d6c38f40 by task kworker/0:1/23
>
> CPU: 0 PID: 23 Comm: kworker/0:1 Not tainted 4.16.0-rc3+ #332
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Workqueue: hwsim_wq destroy_radio
> Call Trace:
> ÂÂ__dump_stack lib/dump_stack.c:17 [inline]
> ÂÂdump_stack+0x194/0x24d lib/dump_stack.c:53
> ÂÂprint_address_description+0x73/0x250 mm/kasan/report.c:256
> ÂÂkasan_report_error mm/kasan/report.c:354 [inline]
> ÂÂkasan_report+0x23b/0x360 mm/kasan/report.c:412
> ÂÂ__asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:430
> ÂÂstrlen+0x85/0xa0 lib/string.c:482
> ÂÂstrlen include/linux/string.h:267 [inline]
> ÂÂhwsim_mcast_del_radio drivers/net/wireless/mac80211_hwsim.c:2835 [inline]
> ÂÂmac80211_hwsim_del_radio+0x168/0x3b0
> drivers/net/wireless/mac80211_hwsim.c:2854
> ÂÂdestroy_radio+0x9d/0x100 drivers/net/wireless/mac80211_hwsim.c:3396
> ÂÂprocess_one_work+0xc47/0x1bb0 kernel/workqueue.c:2113
> ÂÂworker_thread+0x223/0x1990 kernel/workqueue.c:2247
> ÂÂkthread+0x33c/0x400 kernel/kthread.c:238
> ÂÂret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:406
>
> Allocated by task 6226:
> ÂÂsave_stack+0x43/0xd0 mm/kasan/kasan.c:447
> ÂÂset_track mm/kasan/kasan.c:459 [inline]
> ÂÂkasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:552
> ÂÂ__do_kmalloc mm/slab.c:3705 [inline]
> ÂÂ__kmalloc_track_caller+0x15e/0x760 mm/slab.c:3720
> ÂÂkvasprintf+0xa9/0x130 lib/kasprintf.c:25
> ÂÂkvasprintf_const+0x56/0x160 lib/kasprintf.c:49
> ÂÂkobject_set_name_vargs+0x5b/0x140 lib/kobject.c:263
> ÂÂdev_set_name+0xb4/0xf0 drivers/base/core.c:1649
> ÂÂwiphy_new_nm+0x910/0x21d0 net/wireless/core.c:451
> ÂÂieee80211_alloc_hw_nm+0x4b4/0x2180 net/mac80211/main.c:531
> ÂÂmac80211_hwsim_new_radio+0x227/0x2cd0
> drivers/net/wireless/mac80211_hwsim.c:2537
> ÂÂhwsim_new_radio_nl+0x67a/0x8c0 drivers/net/wireless/mac80211_hwsim.c:3213
> ÂÂgenl_family_rcv_msg+0x7b7/0xfb0 net/netlink/genetlink.c:599
> ÂÂgenl_rcv_msg+0xb2/0x140 net/netlink/genetlink.c:624
> ÂÂnetlink_rcv_skb+0x14b/0x380 net/netlink/af_netlink.c:2444
> ÂÂgenl_rcv+0x28/0x40 net/netlink/genetlink.c:635
> ÂÂnetlink_unicast_kernel net/netlink/af_netlink.c:1308 [inline]
> ÂÂnetlink_unicast+0x4c4/0x6b0 net/netlink/af_netlink.c:1334
> ÂÂnetlink_sendmsg+0xa4a/0xe60 net/netlink/af_netlink.c:1897
> ÂÂsock_sendmsg_nosec net/socket.c:630 [inline]
> ÂÂsock_sendmsg+0xca/0x110 net/socket.c:640
> ÂÂ___sys_sendmsg+0x767/0x8b0 net/socket.c:2046
> ÂÂ__sys_sendmsg+0xe5/0x210 net/socket.c:2080
> ÂÂSYSC_sendmsg net/socket.c:2091 [inline]
> ÂÂSyS_sendmsg+0x2d/0x50 net/socket.c:2087
> ÂÂdo_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
> ÂÂentry_SYSCALL_64_after_hwframe+0x42/0xb7
>
> Freed by task 5:
> ÂÂsave_stack+0x43/0xd0 mm/kasan/kasan.c:447
> ÂÂset_track mm/kasan/kasan.c:459 [inline]
> ÂÂ__kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:520
> ÂÂkasan_slab_free+0xe/0x10 mm/kasan/kasan.c:527
> ÂÂ__cache_free mm/slab.c:3485 [inline]
> ÂÂkfree+0xd9/0x260 mm/slab.c:3800
> ÂÂkfree_const+0x31/0x40 mm/util.c:38
> ÂÂkobject_rename+0x1b3/0x2a0 lib/kobject.c:501
> ÂÂdevice_rename+0x147/0x1f0 drivers/base/core.c:2648
> ÂÂcfg80211_switch_netns+0x1fa/0x470 net/wireless/core.c:192
> ÂÂcfg80211_pernet_exit+0x93/0xc0 net/wireless/core.c:1336
> ÂÂops_exit_list.isra.6+0xae/0x150 net/core/net_namespace.c:142
> ÂÂcleanup_net+0x6a1/0xcb0 net/core/net_namespace.c:517
> ÂÂprocess_one_work+0xc47/0x1bb0 kernel/workqueue.c:2113
> ÂÂworker_thread+0x223/0x1990 kernel/workqueue.c:2247
> ÂÂkthread+0x33c/0x400 kernel/kthread.c:238
> ÂÂret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:406
>
> The buggy address belongs to the object at ffff8801d6c38f40
> ÂÂwhich belongs to the cache kmalloc-32 of size 32
> The buggy address is located 0 bytes inside of
> ÂÂ32-byte region [ffff8801d6c38f40, ffff8801d6c38f60)
> The buggy address belongs to the page:
> page:ffffea00075b0e00 count:1 mapcount:0 mapping:ffff8801d6c38000
> index:0xffff8801d6c38fc1
> flags: 0x2fffc0000000100(slab)
> raw: 02fffc0000000100 ffff8801d6c38000 ffff8801d6c38fc1 000000010000003f
> raw: ffffea00075b0c20 ffffea00075b0f20 ffff8801dac001c0 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
> ÂÂffff8801d6c38e00: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
> ÂÂffff8801d6c38e80: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
>> Âffff8801d6c38f00: 07 fc fc fc fc fc fc fc fb fb fb fb fc fc fc fc
>
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ^
> ÂÂffff8801d6c38f80: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc
> ÂÂffff8801d6c39000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ==================================================================
>
> ---
> This bug is generated by a dumb bot. It may contain errors.
> See https://goo.gl/tpsmEJ for details.
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JFI: As a coincidence, I'm converting pernet_operation and hwsim_net_ops are the last
in drivers directory which is not converted. There is also an issue with hwsim_netgroup,
and I sent a fix today:

https://patchwork.ozlabs.org/patch/879748/

Thanks,
Kirill