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.
Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
---
mm/shmem.c | 23 +++++++++++++----------
1 file changed, 13 insertions(+), 10 deletions(-)
diff --git a/mm/shmem.c b/mm/shmem.c
index 5d39f88..578622e 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2183,17 +2183,17 @@ int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm,
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;
@@ -2206,6 +2206,9 @@ int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm,
/* 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;
}
--
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