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Message-ID: <8f7418e3-816f-4bfd-bf6e-8be68054f55d@oracle.com>
Date: Wed, 25 Oct 2023 23:55:22 -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 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.
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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