On 18.12.2021 12:43, Paraschiv, Andra-Irina wrote:

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.

Thank you, Greg, for helping with the merge of v2 for this patch.

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;

Amazon Development Center (Romania) S.R.L. registered office: 27A Sf. Lazar Street, UBC5, floor 2, Iasi, Iasi County, 700045, Romania. Registered in Romania. Registration number J22/2621/2005.

On 20.12.2021 11:23, Vitaly Kuznetsov wrote:

Andra Paraschiv andraprs@amazon.com writes:

...

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

In case commit 5b78ed24e8ec broke Nitro Enclaves driver, we need to explicitly state this:

Fixes: 5b78ed24e8ec ("mm/pagemap: add mmap_assert_locked() annotations to find_vma*()")

Added to the commit message.

...

---

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);
  

This looks very much like get_user_pages_unlocked(), I think we can use it instead of open-coding it.

Indeed, it's mentioned as well in the comment for get_user_pages_unlocked() this pattern of mmap_read_lock() / get_user_pages() / mmap_read_unlock().

Thank you for the feedback, Vitaly. I sent v2 that includes the mentioned updates.

Thanks, Andra

...

           if (gup_rc < 0) {
                   rc = gup_rc;

-- Vitaly

Amazon Development Center (Romania) S.R.L. registered office: 27A Sf. Lazar Street, UBC5, floor 2, Iasi, Iasi County, 700045, Romania. Registered in Romania. Registration number J22/2621/2005.