From: Yu Zhao <yuzhao@google.com>
To: Alexey Gladkov <legion@kernel.org>
Cc: Jordan Glover <Golden_Miller83@protonmail.ch>,
ebiederm@xmission.com, LKML <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org, containers@lists.linux-foundation.org
Subject: Re: linux 5.14.3: free_user_ns causes NULL pointer dereference
Date: Thu, 30 Sep 2021 16:27:34 -0600 [thread overview]
Message-ID: <CAOUHufZmAjuKyRcmq6GH8dfdZxchykS=BTZDsk-gDAh3LJTe1Q@mail.gmail.com> (raw)
In-Reply-To: <20210930130640.wudkpmn3cmah2cjz@example.org>
On Thu, Sep 30, 2021 at 7:06 AM Alexey Gladkov <legion@kernel.org> wrote:
>
> On Wed, Sep 29, 2021 at 09:39:06PM +0000, Jordan Glover wrote:
> > > I'm still investigating, but I would like to rule out one option.
> > >
> > > Could you check out the patch?
> >
> >
> > Thx, I added it to my kernel and will report in few days.
> > Does this patch try to fix the issue or make it easier to track?
>
> I suspect the error is caused by a race between allow_ucounts() and
> put_ucounts(). I think this patch could solve the problem.
Thanks for your help. Still can reproduce the problem with the change suggested.
[ 7761.885966] ==================================================================
[ 7761.893462] BUG: KASAN: use-after-free in dec_ucount+0x50/0xd8
[ 7761.899491] Write of size 8 at addr ffffff80c537b140 by task
kworker/u16:3/10303
[ 7761.907110]
[ 7761.908668] CPU: 0 PID: 10303 Comm: kworker/u16:3 Not tainted
5.14.0-lockdep+ #1
[ 7761.916289] Hardware name: Google Lazor (rev3+) with KB Backlight (DT)
[ 7761.923021] Workqueue: netns cleanup_net
[ 7761.927106] Call trace:
[ 7761.929648] dump_backtrace+0x0/0x42c
[ 7761.933442] show_stack+0x24/0x30
[ 7761.936878] dump_stack_lvl+0xd0/0x100
[ 7761.940763] print_address_description+0x30/0x304
[ 7761.945628] kasan_report+0x190/0x1d8
[ 7761.949418] kasan_check_range+0x1ac/0x1bc
[ 7761.953655] __kasan_check_write+0x44/0x54
[ 7761.957891] dec_ucount+0x50/0xd8
[ 7761.961334] cleanup_net+0x630/0x718
[ 7761.965036] process_one_work+0x7b4/0x10ec
[ 7761.969274] worker_thread+0x800/0xcf4
[ 7761.973152] kthread+0x2a8/0x358
[ 7761.976496] ret_from_fork+0x10/0x18
[ 7761.980201]
[ 7761.981761] Allocated by task 4840:
[ 7761.985366] kasan_save_stack+0x38/0x68
[ 7761.989342] __kasan_kmalloc+0x9c/0xb8
[ 7761.993222] kmem_cache_alloc_trace+0x2a4/0x370
[ 7761.997905] alloc_ucounts+0x150/0x374
[ 7762.001787] set_cred_ucounts+0x198/0x248
[ 7762.005935] __sys_setresuid+0x31c/0x4f8
[ 7762.009993] __arm64_sys_setresuid+0x84/0x98
[ 7762.014410] invoke_syscall+0xd4/0x2c8
[ 7762.018292] el0_svc_common+0x124/0x200
[ 7762.022265] do_el0_svc_compat+0x54/0x64
[ 7762.026325] el0_svc_compat+0x24/0x34
[ 7762.030124] el0t_32_sync_handler+0xc0/0xf0
[ 7762.034451] el0t_32_sync+0x19c/0x1a0
[ 7762.038241]
[ 7762.039799] Freed by task 0:
[ 7762.042778] kasan_save_stack+0x38/0x68
[ 7762.046747] kasan_set_track+0x28/0x3c
[ 7762.050625] kasan_set_free_info+0x28/0x4c
[ 7762.054857] ____kasan_slab_free+0x118/0x164
[ 7762.059277] __kasan_slab_free+0x18/0x28
[ 7762.063339] kfree+0x2f8/0x500
[ 7762.066505] put_ucounts+0x11c/0x134
[ 7762.070209] put_cred_rcu+0x1bc/0x35c
[ 7762.074006] rcu_core+0xa68/0x1b20
[ 7762.077538] rcu_core_si+0x1c/0x28
[ 7762.081061] __do_softirq+0x4bc/0xedc
[ 7762.084851]
[ 7762.086401] The buggy address belongs to the object at ffffff80c537b100
[ 7762.086401] which belongs to the cache kmalloc-256 of size 256
[ 7762.099267] The buggy address is located 64 bytes inside of
[ 7762.099267] 256-byte region [ffffff80c537b100, ffffff80c537b200)
[ 7762.111248] The buggy address belongs to the page:
[ 7762.116185] page:fffffffe0314de00 refcount:1 mapcount:0
mapping:0000000000000000 index:0xffffff80c537ad00 pfn:0x145378
[ 7762.127180] head:fffffffe0314de00 order:3 compound_mapcount:0
compound_pincount:0
[ 7762.134881] flags: 0x8000000000010200(slab|head|zone=2)
[ 7762.140286] raw: 8000000000010200 fffffffe02799408 fffffffe02020808
ffffff808000c980
[ 7762.148263] raw: ffffff80c537ad00 0000000000200004 00000001ffffffff
0000000000000000
[ 7762.156228] page dumped because: kasan: bad access detected
[ 7762.161974]
[ 7762.163532] Memory state around the buggy address:
[ 7762.168475] ffffff80c537b000: fc fc fc fc fc fc fc fc fc fc fc fc
fc fc fc fc
[ 7762.175915] ffffff80c537b080: fc fc fc fc fc fc fc fc fc fc fc fc
fc fc fc fc
[ 7762.183346] >ffffff80c537b100: fa fb fb fb fb fb fb fb fb fb fb fb
fb fb fb fb
[ 7762.190774] ^
[ 7762.196258] ffffff80c537b180: fb fb fb fb fb fb fb fb fb fb fb fb
fb fb fb fb
[ 7762.203689] ffffff80c537b200: fc fc fc fc fc fc fc fc fc fc fc fc
fc fc fc fc
[ 7762.211125] ==================================================================
next prev parent reply other threads:[~2021-09-30 22:27 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-15 19:49 linux 5.14.3: free_user_ns causes NULL pointer dereference Jordan Glover
2021-09-15 21:02 ` Eric W. Biederman
2021-09-15 22:42 ` Jordan Glover
2021-09-15 23:44 ` Yu Zhao
2021-09-17 16:15 ` Eric W. Biederman
2021-09-17 18:45 ` Yu Zhao
2021-09-15 23:47 ` Jordan Glover
2021-09-16 17:30 ` Eric W. Biederman
2021-09-16 19:14 ` Alexey Gladkov
2021-09-28 13:40 ` Jordan Glover
2021-09-29 17:36 ` Alexey Gladkov
2021-09-29 21:39 ` Jordan Glover
2021-09-30 13:06 ` Alexey Gladkov
2021-09-30 22:27 ` Yu Zhao [this message]
2021-10-04 17:10 ` Eric W. Biederman
2021-10-04 17:19 ` Eric W. Biederman
2021-10-04 21:34 ` Yu Zhao
2021-10-06 7:57 ` Rune Kleveland
2021-10-10 8:59 ` Rune Kleveland
2021-10-11 13:09 ` Hillf Danton
2021-10-12 17:31 ` Eric W. Biederman
2021-10-15 22:10 ` [CFT][PATCH] ucounts: Fix signal ucount refcounting Eric W. Biederman
2021-10-15 23:09 ` Alexey Gladkov
2021-10-16 17:34 ` Eric W. Biederman
2021-10-17 19:35 ` Yu Zhao
2021-10-18 15:35 ` Eric W. Biederman
2021-10-16 2:08 ` Hillf Danton
2021-10-16 18:00 ` Eric W. Biederman
2021-10-17 16:47 ` Rune Kleveland
2021-10-18 6:25 ` Yu Zhao
2021-10-18 10:31 ` Jordan Glover
2021-10-18 16:06 ` [PATCH v2] " Eric W. Biederman
2021-10-18 17:21 ` [PATCH 0/3] ucounts: misc fixes Eric W. Biederman
2021-10-18 17:23 ` [PATCH 1/3] ucounts: Pair inc_rlimit_ucounts with dec_rlimit_ucoutns in commit_creds Eric W. Biederman
2021-10-18 17:23 ` [PATCH 2/3] ucounts: Proper error handling in set_cred_ucounts Eric W. Biederman
2021-10-18 17:24 ` [PATCH 3/3] ucounts: Move get_ucounts from cred_alloc_blank to key_change_session_keyring Eric W. Biederman
2021-10-18 17:54 ` [PATCH 0/4] ucounts: misc cleanups Eric W. Biederman
2021-10-18 17:55 ` [PATCH 1/4] ucounts: In set_cred_ucounts assume new->ucounts is non-NULL Eric W. Biederman
2021-10-18 17:56 ` [PATCH 2/4] ucounts: Remove unnecessary test for NULL ucount in get_ucounts Eric W. Biederman
2021-10-18 17:56 ` [PATCH 3/4] ucounts: Add get_ucounts_or_wrap for clarity Eric W. Biederman
2021-10-18 17:57 ` [PATCH 4/4] ucounts: Use atomic_long_sub_return " Eric W. Biederman
2021-10-18 22:29 ` [PATCH 0/4] ucounts: misc cleanups Yu Zhao
2021-10-18 22:28 ` [PATCH 0/3] ucounts: misc fixes Yu Zhao
2021-10-18 22:26 ` [PATCH v2] ucounts: Fix signal ucount refcounting Yu Zhao
2021-10-06 2:12 ` linux 5.14.3: free_user_ns causes NULL pointer dereference Hillf Danton
2021-10-06 6:22 ` Yu Zhao
2021-10-07 13:28 ` Jordan Glover
2021-10-10 11:26 ` Hillf Danton
2021-10-03 19:37 ` Jordan Glover
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