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From: Alan Stern <stern@rowland.harvard.edu>
To: Pete Zaitcev <zaitcev@redhat.com>
Cc: Greg KH <greg@kroah.com>, USB list <linux-usb@vger.kernel.org>
Subject: Re: [PATCH] usb: mon: Fix a deadlock in usbmon between mmap and read
Date: Wed, 27 Nov 2019 10:07:11 -0500 (EST)	[thread overview]
Message-ID: <Pine.LNX.4.44L0.1911271004190.1484-100000@iolanthe.rowland.org> (raw)
In-Reply-To: <20191126223509.69fb61ed@suzdal.zaitcev.lan>

On Tue, 26 Nov 2019, Pete Zaitcev wrote:

> On Tue, 26 Nov 2019 10:20:14 -0500 (EST)
> Alan Stern <stern@rowland.harvard.edu> wrote:
> 
> > > Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
> > > Reported-by: syzbot+56f9673bb4cdcbeb0e92@syzkaller.appspotmail.com  
> > 
> > Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
> 
> Thanks.
> 
> > Fixes: 46eb14a6e158 ("USB: fix usbmon BUG trigger")
> 
> Indeed... Either I didn't think that one through, or the copy_to_user
> used not to take the mmap_sem.

copy_to_user doesn't, but the fault handler does (the core handler, not
the fault routine in mon_bin.c).  After all, it doesn't want the memory
map to change while a page is being read in to satisfy the fault.

Alan Stern


  parent reply	other threads:[~2019-11-27 15:07 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-26  6:44 [PATCH] usb: mon: Fix a deadlock in usbmon between mmap and read Pete Zaitcev
2019-11-26 15:20 ` Alan Stern
2019-11-27  4:35   ` Pete Zaitcev
2019-11-27  6:55     ` Greg KH
2019-11-27 15:07     ` Alan Stern [this message]
2019-12-05  2:39 Pete Zaitcev

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