* + userfaultfd-shmem-add-i_size-checks.patch added to -mm tree
@ 2018-11-26 20:00 akpm
0 siblings, 0 replies; only message in thread
From: akpm @ 2018-11-26 20:00 UTC (permalink / raw)
To: aarcange, dgilbert, hughd, jannh, mike.kravetz, mm-commits,
peterx, rppt, stable
The patch titled
Subject: userfaultfd: shmem: add i_size checks
has been added to the -mm tree. Its filename is
userfaultfd-shmem-add-i_size-checks.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/userfaultfd-shmem-add-i_size-checks.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/userfaultfd-shmem-add-i_size-checks.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Andrea Arcangeli <aarcange@redhat.com>
Subject: userfaultfd: shmem: add i_size checks
With MAP_SHARED: recheck the i_size after taking the PT lock, to serialize
against truncate with the PT lock. Delete the page from the pagecache if
the i_size_read check fails.
With MAP_PRIVATE: check the i_size after the PT lock before mapping
anonymous memory or zeropages into the MAP_PRIVATE shmem mapping.
A mostly irrelevant cleanup: like we do the delete_from_page_cache()
pagecache removal after dropping the PT lock, the PT lock is a spinlock so
drop it before the sleepable page lock.
Link: http://lkml.kernel.org/r/20181126173452.26955-5-aarcange@redhat.com
Fixes: 4c27fe4c4c84 ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support")
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Hugh Dickins <hughd@google.com>
Reported-by: Jann Horn <jannh@google.com>
Cc: <stable@vger.kernel.org>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
--- a/mm/shmem.c~userfaultfd-shmem-add-i_size-checks
+++ a/mm/shmem.c
@@ -2216,6 +2216,7 @@ static int shmem_mfill_atomic_pte(struct
struct page *page;
pte_t _dst_pte, *dst_pte;
int ret;
+ pgoff_t offset, max_off;
ret = -ENOMEM;
if (!shmem_inode_acct_block(inode, 1))
@@ -2253,6 +2254,12 @@ static int shmem_mfill_atomic_pte(struct
__SetPageSwapBacked(page);
__SetPageUptodate(page);
+ ret = -EFAULT;
+ offset = linear_page_index(dst_vma, dst_addr);
+ max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
+ if (unlikely(offset >= max_off))
+ goto out_release;
+
ret = mem_cgroup_try_charge_delay(page, dst_mm, gfp, &memcg, false);
if (ret)
goto out_release;
@@ -2268,8 +2275,14 @@ static int shmem_mfill_atomic_pte(struct
if (dst_vma->vm_flags & VM_WRITE)
_dst_pte = pte_mkwrite(pte_mkdirty(_dst_pte));
- ret = -EEXIST;
dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
+
+ ret = -EFAULT;
+ max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
+ if (unlikely(offset >= max_off))
+ goto out_release_uncharge_unlock;
+
+ ret = -EEXIST;
if (!pte_none(*dst_pte))
goto out_release_uncharge_unlock;
@@ -2287,13 +2300,14 @@ static int shmem_mfill_atomic_pte(struct
/* No need to invalidate - it was non-present before */
update_mmu_cache(dst_vma, dst_addr, dst_pte);
- unlock_page(page);
pte_unmap_unlock(dst_pte, ptl);
+ unlock_page(page);
ret = 0;
out:
return ret;
out_release_uncharge_unlock:
pte_unmap_unlock(dst_pte, ptl);
+ delete_from_page_cache(page);
out_release_uncharge:
mem_cgroup_cancel_charge(page, memcg, false);
out_release:
--- a/mm/userfaultfd.c~userfaultfd-shmem-add-i_size-checks
+++ a/mm/userfaultfd.c
@@ -33,6 +33,8 @@ static int mcopy_atomic_pte(struct mm_st
void *page_kaddr;
int ret;
struct page *page;
+ pgoff_t offset, max_off;
+ struct inode *inode;
if (!*pagep) {
ret = -ENOMEM;
@@ -73,8 +75,17 @@ static int mcopy_atomic_pte(struct mm_st
if (dst_vma->vm_flags & VM_WRITE)
_dst_pte = pte_mkwrite(pte_mkdirty(_dst_pte));
- ret = -EEXIST;
dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
+ if (dst_vma->vm_file) {
+ /* the shmem MAP_PRIVATE case requires checking the i_size */
+ inode = dst_vma->vm_file->f_inode;
+ offset = linear_page_index(dst_vma, dst_addr);
+ max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
+ ret = -EFAULT;
+ if (unlikely(offset >= max_off))
+ goto out_release_uncharge_unlock;
+ }
+ ret = -EEXIST;
if (!pte_none(*dst_pte))
goto out_release_uncharge_unlock;
@@ -108,11 +119,22 @@ static int mfill_zeropage_pte(struct mm_
pte_t _dst_pte, *dst_pte;
spinlock_t *ptl;
int ret;
+ pgoff_t offset, max_off;
+ struct inode *inode;
_dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr),
dst_vma->vm_page_prot));
- ret = -EEXIST;
dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
+ if (dst_vma->vm_file) {
+ /* the shmem MAP_PRIVATE case requires checking the i_size */
+ inode = dst_vma->vm_file->f_inode;
+ offset = linear_page_index(dst_vma, dst_addr);
+ max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
+ ret = -EFAULT;
+ if (unlikely(offset >= max_off))
+ goto out_unlock;
+ }
+ ret = -EEXIST;
if (!pte_none(*dst_pte))
goto out_unlock;
set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
_
Patches currently in -mm which might be from aarcange@redhat.com are
userfaultfd-use-enoent-instead-of-efault-if-the-atomic-copy-user-fails.patch
userfaultfd-shmem-allocate-anonymous-memory-for-map_private-shmem.patch
userfaultfd-shmem-hugetlbfs-only-allow-to-register-vm_maywrite-vmas.patch
userfaultfd-shmem-add-i_size-checks.patch
userfaultfd-shmem-uffdio_copy-set-the-page-dirty-if-vm_write-is-not-set.patch
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2018-11-27 6:55 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-11-26 20:00 + userfaultfd-shmem-add-i_size-checks.patch added to -mm tree akpm
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.