linux-kernel - Re: [PATCH V3] rxe: Fix a sleep-in-atomic bug in post_one

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Date:   Mon, 5 Jun 2017 11:30:14 +0300
From:   Moni Shoua <monis@...lanox.com>
To:     Jia-Ju Bai <baijiaju1990@....com>
Cc:     yuval.shaia@...cle.com, Sean Hefty <sean.hefty@...el.com>,
        Doug Ledford <dledford@...hat.com>,
        Hal Rosenstock <hal.rosenstock@...il.com>,
        Leon Romanovsky <leon@...nel.org>,
        linux-rdma <linux-rdma@...r.kernel.org>,
        Linux Kernel Mailinglist <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V3] rxe: Fix a sleep-in-atomic bug in post_one_send

> -                       if (qp->is_user && copy_from_user(p, (__user void *)
> -                                           (uintptr_t)sge->addr, sge->length))
> +                       spin_unlock_irqrestore(&qp->sq.sq_lock, *flags);
> +                       err = copy_from_user(p, (__user void *)
> +                                       (uintptr_t)sge->addr, sge->length);
> +                       spin_lock_irqsave(&qp->sq.sq_lock, *flags);
> +                       if (qp->is_user && err)
>                                 return -EFAULT;
qp-_is_user is always false in this function (flow starts from
rxe_post_send_kernel) so this line is a dead code
In fact, this patch seems to add a serious bug when it uses
copy_from_user() from a non user pointer.
Do you agree?