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    SubjectRE: RE: [PATCH] infiniband/i40iw: Fix a use after free in i40iw_cm_event_handler
    Date
    > Subject: Re: RE: [PATCH] infiniband/i40iw: Fix a use after free in
    > i40iw_cm_event_handler
    >
    >
    >
    >
    > > -----原始邮件-----
    > > 发件人: "Saleem, Shiraz" <shiraz.saleem@intel.com>
    > > 发送时间: 2021-03-12 09:13:39 (星期五)
    > > 收件人: "Jason Gunthorpe" <jgg@nvidia.com>, "Lv Yunlong"
    > > <lyl2019@mail.ustc.edu.cn>
    > > 抄送: "Latif, Faisal" <faisal.latif@intel.com>, "dledford@redhat.com"
    > > <dledford@redhat.com>, "linux-rdma@vger.kernel.org"
    > > <linux-rdma@vger.kernel.org>, "linux-kernel@vger.kernel.org"
    > > <linux-kernel@vger.kernel.org>
    > > 主题: RE: [PATCH] infiniband/i40iw: Fix a use after free in
    > > i40iw_cm_event_handler
    > >
    > > > Subject: Re: [PATCH] infiniband/i40iw: Fix a use after free in
    > > > i40iw_cm_event_handler
    > > >
    > > > On Wed, Mar 10, 2021 at 07:14:14PM -0800, Lv Yunlong wrote:
    > > > > In the case of I40IW_CM_EVENT_ABORTED, i40iw_event_connect_error()
    > > > > could be called to free the event->cm_node. However,
    > > > > event->cm_node will be used after and cause use after free. It
    > > > > needs to add flags to inform that event->cm_node has been freed.
    > > > >
    > > > > Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
    > > > > ---
    > > > > drivers/infiniband/hw/i40iw/i40iw_cm.c | 5 ++++-
    > > > > 1 file changed, 4 insertions(+), 1 deletion(-)
    > > >
    > > > This might be OK (though I don't like the free variable), Shiraz??
    > > >
    > >
    > > How was this reproduced? Do you have some call trace leading up to use after
    > free?
    > >
    > > The cm_node refcnt is bumped at creation time and once in i40iw_receive_ilq
    > before packet is processed.
    > > That should protect the cm_node from disappearing in the event handler in the
    > abort event case.
    > > The dec at end of i40iw_receive ilq should be point where the cm_node is freed
    > specifically in the abort case.
    > >
    > > Shiraz
    > >
    >
    > This problem was reported by a path-sensitive analyzer developed by our Security
    > Lab(Loccs).
    > The analyzer reported that there is a feasible path to free event->cm_node and use
    > it after, and that is what i described in the first commit.
    >

    OK. I don’t think that an extra dec refcnt in itself for the abort case is enough evidence to
    say that the cm_node is freed in i40iw_event_connect_error.

    Shiraz

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