linux-kernel - Re: [PATCH v2] infiniband: remove WARN that is not kernel bug

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Date:   Mon, 21 Nov 2016 14:14:08 +0200
From:   Leon Romanovsky <leon@...nel.org>
To:     Dmitry Vyukov <dvyukov@...gle.com>
Cc:     syzkaller <syzkaller@...glegroups.com>,
        Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
        Valdis.Kletnieks@...edu, dledford@...hat.com, sean.hefty@...el.com,
        Hal Rosenstock <hal.rosenstock@...il.com>,
        linux-rdma@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] infiniband: remove WARN that is not kernel bug

On Mon, Nov 21, 2016 at 12:48:35PM +0100, Dmitry Vyukov wrote:
> On Mon, Nov 21, 2016 at 12:44 PM, Leon Romanovsky <leon@...nel.org> wrote:
> > On Mon, Nov 21, 2016 at 11:30:21AM +0100, Dmitry Vyukov wrote:
> >> On Mon, Nov 21, 2016 at 11:25 AM, Miroslav Benes <mbenes@...e.cz> wrote:
> >> > On Mon, 21 Nov 2016, Dmitry Vyukov wrote:
> >> >
> >> >> WARNINGs mean kernel bugs.
> >> >> The one in ucma_write() points to user programming error
> >> >> or a malicious attempt. This is not a kernel bug, remove it.
> >> >>
> >> >> BUG/WARNs that are not kernel bugs hinder automated testing effots.
> >> >>
> >> >> Signed-off-by: Dmitry Vyukov <dvyukov@...gle.com>
> >> >> Cc: Doug Ledford <dledford@...hat.com>
> >> >> Cc: Sean Hefty <sean.hefty@...el.com>
> >> >> Cc: Hal Rosenstock <hal.rosenstock@...il.com>
> >> >> Cc: Leon Romanovsky <leon@...nel.org>
> >> >> Cc: linux-rdma@...r.kernel.org
> >> >> Cc: linux-kernel@...r.kernel.org
> >> >> Cc: syzkaller@...glegroups.com
> >> >>
> >> >> ---
> >> >> Changes since v1:
> >> >>  - added printk_once
> >> >> ---
> >> >>  drivers/infiniband/core/ucma.c | 5 ++++-
> >> >>  1 file changed, 4 insertions(+), 1 deletion(-)
> >> >>
> >> >> diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
> >> >> index 9520154..405d0ce 100644
> >> >> --- a/drivers/infiniband/core/ucma.c
> >> >> +++ b/drivers/infiniband/core/ucma.c
> >> >> @@ -1584,8 +1584,11 @@ static ssize_t ucma_write(struct file *filp, const char __user *buf,
> >> >>       struct rdma_ucm_cmd_hdr hdr;
> >> >>       ssize_t ret;
> >> >>
> >> >> -     if (WARN_ON_ONCE(!ib_safe_file_access(filp)))
> >> >> +     if (!ib_safe_file_access(filp)) {
> >> >> +             printk_once("ucma_write: process %d (%s) tried to do something hinky\n",
> >> >> +                     task_tgid_vnr(current), current->comm);
> >> >>               return -EACCES;
> >> >> +     }
> >> >>
> >> >>       if (len < sizeof(hdr))
> >> >>               return -EINVAL;
> >> >
> >> > FWIW, WARN_ON_ONCE came with commit e6bd18f57aad ("IB/security: Restrict
> >> > use of the write() interface"). Would it make sense to change the other
> >> > places as well?
> >>
> >>
> >> I guess so.
> >> Can I ask somebody of infiniband maintainers to take care of this?
> >
> > Please see below,
> > Hope it helps.
>
> In ib_ucm_write function there is a wrong prefix:
>
> + pr_err_once("ucm_write: process %d (%s) tried to do something hinky\n",

I did it intentionally to have the same errors for all flows.

>
> Otherwise looks good. Thanks.

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