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[84.3.50.134]) by smtp.gmail.com with ESMTPSA id j14sm19107399wrp.16.2019.11.11.22.32.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 11 Nov 2019 22:32:54 -0800 (PST) Date: Tue, 12 Nov 2019 07:32:52 +0100 From: Ingo Molnar To: Thomas Gleixner Cc: LKML , x86@kernel.org, Linus Torvalds , Andy Lutomirski , Stephen Hemminger , Willy Tarreau , Juergen Gross , Sean Christopherson , "H. Peter Anvin" Subject: Re: [patch V2 14/16] x86/iopl: Restrict iopl() permission scope Message-ID: <20191112063252.GB100264@gmail.com> References: <20191111220314.519933535@linutronix.de> <20191111223052.881699933@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Thomas Gleixner wrote: > --- a/arch/x86/kernel/ioport.c > +++ b/arch/x86/kernel/ioport.c > @@ -18,12 +18,15 @@ static atomic64_t io_bitmap_sequence; > > void io_bitmap_share(struct task_struct *tsk) > { > - /* > - * Take a refcount on current's bitmap. It can be used by > - * both tasks as long as none of them changes the bitmap. > - */ > - refcount_inc(¤t->thread.io_bitmap->refcnt); > - tsk->thread.io_bitmap = current->thread.io_bitmap; > + /* Can be NULL when current->thread.iopl_emul == 3 */ > + if (current->thread.io_bitmap) { > + /* > + * Take a refcount on current's bitmap. It can be used by > + * both tasks as long as none of them changes the bitmap. > + */ > + refcount_inc(¤t->thread.io_bitmap->refcnt); > + tsk->thread.io_bitmap = current->thread.io_bitmap; > + } Minor side note: whitespace damage managed to slip in that code, see the fix below. Thanks, Ingo arch/x86/kernel/ioport.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/arch/x86/kernel/ioport.c b/arch/x86/kernel/ioport.c index f87844e22ec9..ee37a1c25ecc 100644 --- a/arch/x86/kernel/ioport.c +++ b/arch/x86/kernel/ioport.c @@ -17,16 +17,16 @@ static atomic64_t io_bitmap_sequence; void io_bitmap_share(struct task_struct *tsk) - { - /* Can be NULL when current->thread.iopl_emul == 3 */ - if (current->thread.io_bitmap) { - /* - * Take a refcount on current's bitmap. It can be used by - * both tasks as long as none of them changes the bitmap. - */ - refcount_inc(¤t->thread.io_bitmap->refcnt); - tsk->thread.io_bitmap = current->thread.io_bitmap; - } +{ + /* Can be NULL when current->thread.iopl_emul == 3 */ + if (current->thread.io_bitmap) { + /* + * Take a refcount on current's bitmap. It can be used by + * both tasks as long as none of them changes the bitmap. + */ + refcount_inc(¤t->thread.io_bitmap->refcnt); + tsk->thread.io_bitmap = current->thread.io_bitmap; + } set_tsk_thread_flag(tsk, TIF_IO_BITMAP); }