Re: [PATCH v6 04/12] drivers/infiniband: make setup_ctxt always get a nul terminated task comm

From: Yafang Shao <laoar.shao@gmail.com>
To: Kees Cook <keescook@chromium.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>,
	Petr Mladek <pmladek@suse.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Valentin Schneider <valentin.schneider@arm.com>,
	Qiang Zhang <qiang.zhang@windriver.com>,
	robdclark <robdclark@chromium.org>,
	christian <christian@brauner.io>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Ingo Molnar <mingo@redhat.com>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	David Miller <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>, Martin Lau <kafai@fb.com>,
	Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
	john fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>,
	dennis.dalessandro@cornelisnetworks.com,
	mike.marciniszyn@cornelisnetworks.com, dledford@redhat.com,
	jgg@ziepe.ca, linux-rdma@vger.kernel.org,
	netdev <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
	"linux-perf-use." <linux-perf-users@vger.kernel.org>,
	linux-fsdevel@vger.kernel.org, Linux MM <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>,
	kernel test robot <oliver.sang@intel.com>,
	kbuild test robot <lkp@intel.com>,
	Andrii Nakryiko <andrii.nakryiko@gmail.com>
Subject: Re: [PATCH v6 04/12] drivers/infiniband: make setup_ctxt always get a nul terminated task comm
Date: Tue, 26 Oct 2021 09:52:34 +0800	[thread overview]
Message-ID: <CALOAHbDyo1H7hg__h+aCHCa-BZX5z=wtfM+cc+gNSj+4U9nRUQ@mail.gmail.com> (raw)
In-Reply-To: <202110251415.9AD37837@keescook>

On Tue, Oct 26, 2021 at 5:16 AM Kees Cook <keescook@chromium.org> wrote:
>
> On Mon, Oct 25, 2021 at 08:33:07AM +0000, Yafang Shao wrote:
> > Use strscpy_pad() instead of strlcpy() to make the comm always nul
> > terminated. As the comment above the hard-coded 16, we can replace it
> > with TASK_COMM_LEN, then it will adopt to the comm size change.
> >
> > Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
> > Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
> > Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
> > Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
> > Cc: Peter Zijlstra <peterz@infradead.org>
> > Cc: Steven Rostedt <rostedt@goodmis.org>
> > Cc: Al Viro <viro@zeniv.linux.org.uk>
> > Cc: Kees Cook <keescook@chromium.org>
> > Cc: Petr Mladek <pmladek@suse.com>
> > ---
> >  drivers/infiniband/hw/qib/qib.h          | 2 +-
> >  drivers/infiniband/hw/qib/qib_file_ops.c | 2 +-
> >  2 files changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/infiniband/hw/qib/qib.h b/drivers/infiniband/hw/qib/qib.h
> > index 9363bccfc6e7..a8e1c30c370f 100644
> > --- a/drivers/infiniband/hw/qib/qib.h
> > +++ b/drivers/infiniband/hw/qib/qib.h
> > @@ -196,7 +196,7 @@ struct qib_ctxtdata {
> >       pid_t pid;
> >       pid_t subpid[QLOGIC_IB_MAX_SUBCTXT];
> >       /* same size as task_struct .comm[], command that opened context */
> > -     char comm[16];
> > +     char comm[TASK_COMM_LEN];
> >       /* pkeys set by this use of this ctxt */
> >       u16 pkeys[4];
> >       /* so file ops can get at unit */
> > diff --git a/drivers/infiniband/hw/qib/qib_file_ops.c b/drivers/infiniband/hw/qib/qib_file_ops.c
> > index 63854f4b6524..7ab2b448c183 100644
> > --- a/drivers/infiniband/hw/qib/qib_file_ops.c
> > +++ b/drivers/infiniband/hw/qib/qib_file_ops.c
> > @@ -1321,7 +1321,7 @@ static int setup_ctxt(struct qib_pportdata *ppd, int ctxt,
> >       rcd->tid_pg_list = ptmp;
> >       rcd->pid = current->pid;
> >       init_waitqueue_head(&dd->rcd[ctxt]->wait);
> > -     strlcpy(rcd->comm, current->comm, sizeof(rcd->comm));
> > +     strscpy_pad(rcd->comm, current->comm, sizeof(rcd->comm));
>
> This should use (the adjusted) get_task_comm() instead of leaving this
> open-coded.
>

Sure, that is better.

> >       ctxt_fp(fp) = rcd;
> >       qib_stats.sps_ctxts++;
> >       dd->freectxts--;
> > --
> > 2.17.1
> >
>
> --
> Kees Cook

-- 
Thanks
Yafang