The patch titled
Subject: userfaultfd: shmem: avoid leaking blocks and used blocks in UFFDIO_COPY
has been added to the -mm tree. Its filename is
userfaultfd-shmem-avoid-leaking-blocks-and-used-blocks-in-uffdio_copy.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/userfaultfd-shmem-avoid-leaking-blocks-and-used-blocks-in-uffdio_copy.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/userfaultfd-shmem-avoid-leaking-blocks-and-used-blocks-in-uffdio_copy.patch
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------------------------------------------------------
From: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Subject: userfaultfd: shmem: avoid leaking blocks and used blocks in UFFDIO_COPY
If the atomic copy_user fails because of a real dangling userland
pointer, we won't go back into the shmem method, so when the method
returns it must not leave anything charged up, except the page itself.
Link: http://lkml.kernel.org/r/20161216144821.5183-37-aarcange@xxxxxxxxxx
Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: "Dr. David Alan Gilbert" <dgilbert@xxxxxxxxxx>
Cc: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx>
Cc: Michael Rapoport <RAPOPORT@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/shmem.c | 23 +++++++++++++----------
1 file changed, 13 insertions(+), 10 deletions(-)
diff -puN mm/shmem.c~userfaultfd-shmem-avoid-leaking-blocks-and-used-blocks-in-uffdio_copy mm/shmem.c
--- a/mm/shmem.c~userfaultfd-shmem-avoid-leaking-blocks-and-used-blocks-in-uffdio_copy
+++ a/mm/shmem.c
@@ -2207,17 +2207,17 @@ int shmem_mcopy_atomic_pte(struct mm_str
pte_t _dst_pte, *dst_pte;
int ret;
- if (!*pagep) {
- ret = -ENOMEM;
- if (shmem_acct_block(info->flags, 1))
- goto out;
- if (sbinfo->max_blocks) {
- if (percpu_counter_compare(&sbinfo->used_blocks,
- sbinfo->max_blocks) >= 0)
- goto out_unacct_blocks;
- percpu_counter_inc(&sbinfo->used_blocks);
- }
+ ret = -ENOMEM;
+ if (shmem_acct_block(info->flags, 1))
+ goto out;
+ if (sbinfo->max_blocks) {
+ if (percpu_counter_compare(&sbinfo->used_blocks,
+ sbinfo->max_blocks) >= 0)
+ goto out_unacct_blocks;
+ percpu_counter_inc(&sbinfo->used_blocks);
+ }
+ if (!*pagep) {
page = shmem_alloc_page(gfp, info, pgoff);
if (!page)
goto out_dec_used_blocks;
@@ -2230,6 +2230,9 @@ int shmem_mcopy_atomic_pte(struct mm_str
/* fallback to copy_from_user outside mmap_sem */
if (unlikely(ret)) {
*pagep = page;
+ if (sbinfo->max_blocks)
+ percpu_counter_add(&sbinfo->used_blocks, -1);
+ shmem_unacct_blocks(info->flags, 1);
/* don't free the page */
return -EFAULT;
}
_
Patches currently in -mm which might be from aarcange@xxxxxxxxxx are
userfaultfd-document-_ior-_iow.patch
userfaultfd-correct-comment-about-uffd_feature_pagefault_flag_wp.patch
userfaultfd-convert-bug-to-warn_on_once.patch
userfaultfd-use-vma_is_anonymous.patch
userfaultfd-non-cooperative-report-all-available-features-to-userland.patch
userfaultfd-non-cooperative-add-fork-event-build-warning-fix.patch
userfaultfd-non-cooperative-optimize-mremap_userfaultfd_complete.patch
userfaultfd-non-cooperative-avoid-madv_dontneed-race-condition.patch
userfaultfd-non-cooperative-wake-userfaults-after-uffdio_unregister.patch
userfaultfd-hugetlbfs-gup-support-vm_fault_retry.patch
userfaultfd-hugetlbfs-uffd_feature_missing_hugetlbfs.patch
userfaultfd-shmem-add-tlbflushh-header-for-microblaze.patch
userfaultfd-shmem-lock-the-page-before-adding-it-to-pagecache.patch
userfaultfd-shmem-avoid-leaking-blocks-and-used-blocks-in-uffdio_copy.patch
userfaultfd-hugetlbfs-uffd_feature_missing_shmem.patch
userfaultfd-selftest-test-uffdio_zeropage-on-all-memory-types.patch
mm-mprotect-use-pmd_trans_unstable-instead-of-taking-the-pmd_lock.patch
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