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authorAndrea Arcangeli <aarcange@redhat.com>2018-11-30 14:09:37 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-12-08 13:03:37 +0100
commitaf3edb30cddfcc1eace505af10d08826a9522dbe (patch)
tree73a0f659318a3ef9d80ff02c6d78e171dd65d8fd /mm/shmem.c
parent683b47330c498a7bb90b1e863f63c9b5035dbba9 (diff)
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userfaultfd: shmem: add i_size checks
commit e2a50c1f64145a04959df2442305d57307e5395a upstream. 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> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm/shmem.c')
-rw-r--r--mm/shmem.c18
1 files changed, 16 insertions, 2 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index 9f856ecda73b..581e7baf0478 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2244,6 +2244,7 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm,
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))
@@ -2281,6 +2282,12 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm,
__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(page, dst_mm, gfp, &memcg, false);
if (ret)
goto out_release;
@@ -2299,8 +2306,14 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm,
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;
@@ -2318,13 +2331,14 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm,
/* 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: