Re: [PATCH v1 ] nitro_enclaves: Add mmap_read_lock() for the get_user_pages() call - Paraschiv, Andra-Irina

From: "Paraschiv, Andra-Irina" <andraprs@amazon.com>
To: linux-kernel <linux-kernel@vger.kernel.org>,
	Greg KH <gregkh@linuxfoundation.org>
Cc: Alexandru Ciobotaru <alcioa@amazon.com>,
	Alexandru Vasile <lexnv@amazon.com>,
	Marcelo Cerri <marcelo.cerri@canonical.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	Stefano Garzarella <sgarzare@redhat.com>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	Tim Gardner <tim.gardner@canonical.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>, kvm <kvm@vger.kernel.org>,
	ne-devel-upstream <ne-devel-upstream@amazon.com>,
	stable <stable@vger.kernel.org>
Subject: Re: [PATCH v1 ] nitro_enclaves: Add mmap_read_lock() for the get_user_pages() call
Date: Sat, 18 Dec 2021 12:43:24 +0200	[thread overview]
Message-ID: <fccc4545-2a8e-df40-f7ba-ae48651dda39@amazon.com> (raw)
In-Reply-To: <20211218103525.26739-1-andraprs@amazon.com>

On 18.12.2021 12:35, Andra Paraschiv wrote:
> After commit 5b78ed24e8ec (mm/pagemap: add mmap_assert_locked()
> annotations to find_vma*()), the call to get_user_pages() will trigger
> the mmap assert.
> 
> static inline void mmap_assert_locked(struct mm_struct *mm)
> {
> 	lockdep_assert_held(&mm->mmap_lock);
> 	VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_lock), mm);
> }
> 
> [   62.521410] kernel BUG at include/linux/mmap_lock.h:156!
> ...........................................................
> [   62.538938] RIP: 0010:find_vma+0x32/0x80
> ...........................................................
> [   62.605889] Call Trace:
> [   62.608502]  <TASK>
> [   62.610956]  ? lock_timer_base+0x61/0x80
> [   62.614106]  find_extend_vma+0x19/0x80
> [   62.617195]  __get_user_pages+0x9b/0x6a0
> [   62.620356]  __gup_longterm_locked+0x42d/0x450
> [   62.623721]  ? finish_wait+0x41/0x80
> [   62.626748]  ? __kmalloc+0x178/0x2f0
> [   62.629768]  ne_set_user_memory_region_ioctl.isra.0+0x225/0x6a0 [nitro_enclaves]
> [   62.635776]  ne_enclave_ioctl+0x1cf/0x6d7 [nitro_enclaves]
> [   62.639541]  __x64_sys_ioctl+0x82/0xb0
> [   62.642620]  do_syscall_64+0x3b/0x90
> [   62.645642]  entry_SYSCALL_64_after_hwframe+0x44/0xae
> 
> Add mmap_read_lock() for the get_user_pages() call when setting the
> enclave memory regions.
> 
> Signed-off-by: Andra Paraschiv <andraprs@amazon.com>
> Cc: stable@vger.kernel.org
> ---

Greg, can you please include this fix in the queue for v5.16 and then in 
the one for the v5.15 stable tree. Let me know if any updates are 
necessary for the patch.

Thanks,
Andra

>   drivers/virt/nitro_enclaves/ne_misc_dev.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/virt/nitro_enclaves/ne_misc_dev.c b/drivers/virt/nitro_enclaves/ne_misc_dev.c
> index 8939612ee0e0..6c51ff024036 100644
> --- a/drivers/virt/nitro_enclaves/ne_misc_dev.c
> +++ b/drivers/virt/nitro_enclaves/ne_misc_dev.c
> @@ -886,8 +886,13 @@ static int ne_set_user_memory_region_ioctl(struct ne_enclave *ne_enclave,
>   			goto put_pages;
>   		}
>   
> +		mmap_read_lock(current->mm);
> +
>   		gup_rc = get_user_pages(mem_region.userspace_addr + memory_size, 1, FOLL_GET,
>   					ne_mem_region->pages + i, NULL);
> +
> +		mmap_read_unlock(current->mm);
> +
>   		if (gup_rc < 0) {
>   			rc = gup_rc;
>   

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