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Message-ID: <489dd10f-928c-4479-9633-59eedf9b60dd@oracle.com>
Date: Thu, 26 Oct 2023 00:19:32 -0700
From: Si-Wei Liu <si-wei.liu@...cle.com>
To: "Michael S. Tsirkin" <mst@...hat.com>
Cc: jasowang@...hat.com, virtualization@...ts.linux-foundation.org,
sfr@...b.auug.org.au, leiyang@...hat.com,
linux-kernel@...r.kernel.org, linux-next@...r.kernel.org
Subject: Re: [PATCH] vhost-vdpa: fix use-after-free in _compat_vdpa_reset
On 10/25/2023 11:55 PM, Si-Wei Liu wrote:
>
>
> On 10/25/2023 10:26 PM, Michael S. Tsirkin wrote:
>> On Wed, Oct 25, 2023 at 04:13:14PM -0700, Si-Wei Liu wrote:
>>> When the vhost-vdpa device is being closed, vhost_vdpa_cleanup()
>>> doesn't
>>> clean up the vqs pointer after free. This could lead to use-after-tree
>>> when _compat_vdpa_reset() tries to access the vqs that are freed
>>> already.
>>> Fix is to set vqs pointer to NULL at the end of vhost_vdpa_cleanup()
>>> after getting freed, which is guarded by atomic opened state.
>>>
>>> BUG: unable to handle page fault for address: 00000001005b4af4
>>> #PF: supervisor read access in kernel mode
>>> #PF: error_code(0x0000) - not-present page
>>> PGD 16a80a067 P4D 0
>>> Oops: 0000 [#1] PREEMPT SMP NOPTI
>>> CPU: 4 PID: 40387 Comm: qemu-kvm Not tainted 6.6.0-rc7+ #3
>>> Hardware name: Dell Inc. PowerEdge R750/0PJ80M, BIOS 1.8.2
>>> 09/14/2022
>>> RIP: 0010:_compat_vdpa_reset.isra.0+0x27/0xb0 [vhost_vdpa]
>>> Code: 90 90 90 0f 1f 44 00 00 41 55 4c 8d ae 08 03 00 00 41 54 55 48
>>> 89 f5 53 4c 8b a6 00 03 00 00 48 85 ff 74 49 48 8b 07 4c 89 ef
>>> <48> 8b
>>> 80 88 45 00 00 48 c1 e8 08 48 83 f0 01 89 c3 e8 73 5e 9b dc
>>> RSP: 0018:ff73a85762073ba0 EFLAGS: 00010286
>>> RAX: 00000001005b056c RBX: ff32b13ca6994c68 RCX: 0000000000000002
>>> RDX: 0000000000000001 RSI: ff32b13c07559000 RDI: ff32b13c07559308
>>> RBP: ff32b13c07559000 R08: 0000000000000000 R09: ff32b12ca497c0f0
>>> R10: ff73a85762073c58 R11: 0000000c106f9de3 R12: ff32b12c95b1d050
>>> R13: ff32b13c07559308 R14: ff32b12d0ddc5100 R15: 0000000000008002
>>> FS: 00007fec5b8cbf80(0000) GS:ff32b13bbfc80000(0000)
>>> knlGS:0000000000000000
>>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>> CR2: 00000001005b4af4 CR3: 000000015644a003 CR4: 0000000000773ee0
>>> PKRU: 55555554
>>> Call Trace:
>>> <TASK>
>>> ? __die+0x20/0x70
>>> ? page_fault_oops+0x76/0x170
>>> ? exc_page_fault+0x65/0x150
>>> ? asm_exc_page_fault+0x22/0x30
>>> ? _compat_vdpa_reset.isra.0+0x27/0xb0 [vhost_vdpa]
>>> vhost_vdpa_open+0x57/0x280 [vhost_vdpa]
>>> ? __pfx_chrdev_open+0x10/0x10
>>> chrdev_open+0xc6/0x260
>>> ? __pfx_chrdev_open+0x10/0x10
>>> do_dentry_open+0x16e/0x530
>>> do_open+0x21c/0x400
>>> path_openat+0x111/0x290
>>> do_filp_open+0xb2/0x160
>>> ? __check_object_size.part.0+0x5e/0x140
>>> do_sys_openat2+0x96/0xd0
>>> __x64_sys_openat+0x53/0xa0
>>> do_syscall_64+0x59/0x90
>>> ? syscall_exit_to_user_mode+0x22/0x40
>>> ? do_syscall_64+0x69/0x90
>>> ? syscall_exit_to_user_mode+0x22/0x40
>>> ? do_syscall_64+0x69/0x90
>>> ? do_syscall_64+0x69/0x90
>>> ? syscall_exit_to_user_mode+0x22/0x40
>>> ? do_syscall_64+0x69/0x90
>>> ? exc_page_fault+0x65/0x150
>>> entry_SYSCALL_64_after_hwframe+0x6e/0xd8
>>>
>>> Fixes: 10cbf8dfaf93 ("vhost-vdpa: clean iotlb map during reset for
>>> older userspace")
>>> Fixes: ac7e98c73c05 ("vhost-vdpa: fix NULL pointer deref in
>>> _compat_vdpa_reset")
>> So these two are all in next correct?
>>
>> I really do not like it how 10cbf8dfaf936e3ef1f5d7fdc6e9dada268ba6bb
>> introduced a regression and then apparently we keep fixing things up?
> Sorry my bad. The latest one should be all of it.
>
>>
>> Can I squash these 3 commits?
> Sure. Or if you want me to send a v5 with all 3 commits squashed in, I
> can do for sure.
Saw you squashed it with the 2 fixups in place, thank you! Sent a v5
anyway, just in case if you need a fresh series.
Thanks,
-Siwei
>
> Thanks,
> -Siwei
>>
>>
>>> Reported-by: Lei Yang <leiyang@...hat.com>
>>> Closes:
>>> https://lore.kernel.org/all/CAPpAL=yHDqn1AztEcN3MpS8o4M+BL_HVy02FdpiHN7DWd91HwQ@mail.gmail.com/
>>> Signed-off-by: Si-Wei Liu <si-wei.liu@...cle.com>
>>> ---
>>> drivers/vhost/vdpa.c | 1 +
>>> 1 file changed, 1 insertion(+)
>>>
>>> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
>>> index 9a2343c45df0..30df5c58db73 100644
>>> --- a/drivers/vhost/vdpa.c
>>> +++ b/drivers/vhost/vdpa.c
>>> @@ -1355,6 +1355,7 @@ static void vhost_vdpa_cleanup(struct
>>> vhost_vdpa *v)
>>> vhost_vdpa_free_domain(v);
>>> vhost_dev_cleanup(&v->vdev);
>>> kfree(v->vdev.vqs);
>>> + v->vdev.vqs = NULL;
>>> }
>>> static int vhost_vdpa_open(struct inode *inode, struct file *filep)
>>> --
>>> 2.39.3
>
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