lkml.org 
[lkml]   [2018]   [Dec]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 1/1] userfaultfd: check VM_MAYWRITE was set after verifying the uffd is registered
Date
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);
\
 
 \ /
  Last update: 2018-12-06 22:20    [W:0.034 / U:29.680 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site