From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-f198.google.com (mail-qk0-f198.google.com [209.85.220.198]) by kanga.kvack.org (Postfix) with ESMTP id 1AA386B02BB for ; Wed, 2 Nov 2016 15:34:13 -0400 (EDT) Received: by mail-qk0-f198.google.com with SMTP id o68so24650623qkf.3 for ; Wed, 02 Nov 2016 12:34:13 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id v54si1940196qtv.30.2016.11.02.12.34.12 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 02 Nov 2016 12:34:12 -0700 (PDT) From: Andrea Arcangeli Subject: [PATCH 29/33] userfaultfd: shmem: avoid leaking blocks and used blocks in UFFDIO_COPY Date: Wed, 2 Nov 2016 20:34:01 +0100 Message-Id: <1478115245-32090-30-git-send-email-aarcange@redhat.com> In-Reply-To: <1478115245-32090-1-git-send-email-aarcange@redhat.com> References: <1478115245-32090-1-git-send-email-aarcange@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: linux-mm@kvack.org, Michael Rapoport , "Dr. David Alan Gilbert"@v2.random, " , Mike Kravetz , Shaohua Li , Pavel Emelyanov "@v2.random 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 --- 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; } -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org