[PATCH v2 ] nitro_enclaves: Use get_user_pages_unlocked() call to handle mmap assert

Andra Paraschiv
2021-12-20T19:59:47Z

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

Use get_user_pages_unlocked() when setting the enclave memory regions.
That's a similar pattern as mmap_read_lock() used together with
get_user_pages().

Fixes: 5b78ed24e8ec ("mm/pagemap: add mmap_assert_locked() annotations to find_vma*()")
Signed-off-by: Andra Paraschiv <andraprs@amazon.com>
Cc: stable@vger.kernel.org
---
Changelog

v1 -> v2

* Update the commit message to include the reference to the commit
that added the mmap_assert_locked() annotations to find_vma*().
* Use get_user_pages_unlocked() instead of get_user_pages(), that has
a similar pattern as mmap_read_lock() + get_user_pages().
---
drivers/virt/nitro_enclaves/ne_misc_dev.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/virt/nitro_enclaves/ne_misc_dev.c b/drivers/virt/nitro_enclaves/ne_misc_dev.c
index 8939612ee0e0..6894ccb868a6 100644
--- a/drivers/virt/nitro_enclaves/ne_misc_dev.c
+++ b/drivers/virt/nitro_enclaves/ne_misc_dev.c
@@ -886,8 +886,9 @@ static int ne_set_user_memory_region_ioctl(struct ne_enclave *ne_enclave,
goto put_pages;
}

- gup_rc = get_user_pages(mem_region.userspace_addr + memory_size, 1, FOLL_GET,
- ne_mem_region->pages + i, NULL);
+ gup_rc = get_user_pages_unlocked(mem_region.userspace_addr + memory_size, 1,
+ ne_mem_region->pages + i, FOLL_GET);
+
if (gup_rc < 0) {
rc = gup_rc;

--
2.32.0

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