From: Andrea Arcangeli <aarcange@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Hugh Dickins <hughd@google.com>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
Mike Kravetz <mike.kravetz@oracle.com>,
Jann Horn <jannh@google.com>, Peter Xu <peterx@redhat.com>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>
Subject: [PATCH 1/1] userfaultfd: check VM_MAYWRITE was set after verifying the uffd is registered
Date: Thu, 6 Dec 2018 16:20:28 -0500 [thread overview]
Message-ID: <20181206212028.18726-2-aarcange@redhat.com> (raw)
In-Reply-To: <20181206212028.18726-1-aarcange@redhat.com>
Calling UFFDIO_UNREGISTER on virtual ranges not yet registered in uffd
could trigger an harmless false positive WARN_ON. Check the vma is
already registered before checking VM_MAYWRITE to shut off the
false positive warning.
Cc: <stable@vger.kernel.org>
Fixes: 29ec90660d68 ("userfaultfd: shmem/hugetlbfs: only allow to register VM_MAYWRITE vmas")
Reported-by: syzbot+06c7092e7d71218a2c16@syzkaller.appspotmail.com
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---
fs/userfaultfd.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index cd58939dc977..7a85e609fc27 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -1566,7 +1566,6 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
cond_resched();
BUG_ON(!vma_can_userfault(vma));
- WARN_ON(!(vma->vm_flags & VM_MAYWRITE));
/*
* Nothing to do: this vma is already registered into this
@@ -1575,6 +1574,8 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
if (!vma->vm_userfaultfd_ctx.ctx)
goto skip;
+ WARN_ON(!(vma->vm_flags & VM_MAYWRITE));
+
if (vma->vm_start > start)
start = vma->vm_start;
vma_end = min(end, vma->vm_end);
next prev parent reply other threads:[~2018-12-06 21:20 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-06 21:20 [PATCH 0/1] userfaultfd: check VM_MAYWRITE was set after verifying the uffd is registered Andrea Arcangeli
2018-12-06 21:20 ` Andrea Arcangeli [this message]
2018-12-06 21:32 ` [PATCH 1/1] " Mike Rapoport
2018-12-06 22:07 ` Hugh Dickins
2018-12-07 3:43 ` Peter Xu
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