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
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