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

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Date:   Tue, 26 Oct 2021 09:52:34 +0800
From:   Yafang Shao <laoar.shao@...il.com>
To:     Kees Cook <keescook@...omium.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>,
        Petr Mladek <pmladek@...e.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        Valentin Schneider <valentin.schneider@....com>,
        Qiang Zhang <qiang.zhang@...driver.com>,
        robdclark <robdclark@...omium.org>,
        christian <christian@...uner.io>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>, Martin Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        john fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        dennis.dalessandro@...nelisnetworks.com,
        mike.marciniszyn@...nelisnetworks.com, dledford@...hat.com,
        jgg@...pe.ca, linux-rdma@...r.kernel.org,
        netdev <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        "linux-perf-use." <linux-perf-users@...r.kernel.org>,
        linux-fsdevel@...r.kernel.org, Linux MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        kernel test robot <oliver.sang@...el.com>,
        kbuild test robot <lkp@...el.com>,
        Andrii Nakryiko <andrii.nakryiko@...il.com>
Subject: Re: [PATCH v6 04/12] drivers/infiniband: make setup_ctxt always get a
 nul terminated task comm

On Tue, Oct 26, 2021 at 5:16 AM Kees Cook <keescook@...omium.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@...il.com>
> > Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
> > Cc: Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
> > Cc: Andrii Nakryiko <andrii.nakryiko@...il.com>
> > Cc: Peter Zijlstra <peterz@...radead.org>
> > Cc: Steven Rostedt <rostedt@...dmis.org>
> > Cc: Al Viro <viro@...iv.linux.org.uk>
> > Cc: Kees Cook <keescook@...omium.org>
> > Cc: Petr Mladek <pmladek@...e.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