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From: Alan Stern <stern@rowland.harvard.edu>
To: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Cc: "Harley A.W. Lorenzo" <hl1998@protonmail.com>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-safety@lists.elisa.tech" <linux-safety@lists.elisa.tech>,
	"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>
Subject: Re: [PATCH] usb: host: ehci-sched: avoid possible NULL dereference
Date: Tue, 6 Oct 2020 13:58:45 -0400	[thread overview]
Message-ID: <20201006175845.GC423499@rowland.harvard.edu> (raw)
In-Reply-To: <20201006012544.GB399825@rowland.harvard.edu>

On Mon, Oct 05, 2020 at 09:25:44PM -0400, stern@rowland.harvard.edu wrote:
> On Mon, Oct 05, 2020 at 11:19:02PM +0000, Harley A.W. Lorenzo wrote:
> > On Monday, October 5, 2020 5:31 PM, Sudip Mukherjee <sudipm.mukherjee@gmail.com> wrote:
> > 
> > > find_tt() can return NULL or the error value in ERR_PTR() and
> > > dereferencing the return value without checking for the error can
> > > lead to a possible dereference of NULL pointer or ERR_PTR().
> > 
> > Looks fine to me. There is in fact no checks of the return value
> > before a dereference here, and this solves that.
> > 
> > Reviewed-by: Harley A.W. Lorenzo <hl1998@protonmail.com
> 
> No, this patch is wrong.  In fact, these calls to find_tt() cannot 
> return NULL or an ERR_PTR value.

Sudip, if you would prefer to submit a patch that adds comments to those 
call sites explaining that find_tt() will not return NULL or an error, 
that would be okay.

Alan Stern

  reply	other threads:[~2020-10-06 17:58 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-05 21:31 [PATCH] usb: host: ehci-sched: avoid possible NULL dereference Sudip Mukherjee
2020-10-05 23:19 ` Harley A.W. Lorenzo
2020-10-06  1:25   ` stern
2020-10-06 17:58     ` Alan Stern [this message]
2020-10-06  7:19   ` gregkh
2020-10-06  8:31 ` [linux-safety] " Sudip Mukherjee

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