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?
Can I squash these 3 commits?
> Reported-by: Lei Yang <leiyang@xxxxxxxxxx>
> Closes: https://lore.kernel.org/all/CAPpAL=yHDqn1AztEcN3MpS8o4M+BL_HVy02FdpiHN7DWd91HwQ@xxxxxxxxxxxxxx/
> Signed-off-by: Si-Wei Liu <si-wei.liu@xxxxxxxxxx>
> ---
> 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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