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    SubjectRe: [PATCH net -v2] [BUGFIX] bonding: use local function pointer of bond->recv_probe in bond_handle_frame
    Date
    David Miller <davem@davemloft.net> wrote:

    >From: Mitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com>
    >Date: Thu, 13 Oct 2011 11:04:29 +0900
    >
    >> The bond->recv_probe is called in bond_handle_frame() when
    >> a packet is received, but bond_close() sets it to NULL. So,
    >> a panic occurs when both functions work in parallel.
    >>
    >> Why this happen:
    >> After null pointer check of bond->recv_probe, an sk_buff is
    >> duplicated and bond->recv_probe is called in bond_handle_frame.
    >> So, a panic occurs when bond_close() is called between the
    >> check and call of bond->recv_probe.
    >>
    >> Patch:
    >> This patch uses a local function pointer of bond->recv_probe
    >> in bond_handle_frame(). So, it can avoid the null pointer
    >> dereference.
    >>
    >>
    >> Signed-off-by: Mitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com>
    >> Cc: Jay Vosburgh <fubar@us.ibm.com>
    >> Cc: Andy Gospodarek <andy@greyhouse.net>
    >> Cc: Eric Dumazet <eric.dumazet@gmail.com>
    >> Cc: WANG Cong <xiyou.wangcong@gmail.com>
    >
    >Bonding folks please review this, thanks.
    >

    Looks reasonable. Even if by some quirk of timing the
    recv_probe function ends up being entered after bond_close has
    completed, it doesn't look like there is a risk of those functions
    misbehaving (because bond_close doesn't deallocate the data structures).

    -J

    Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>

    ---
    -Jay Vosburgh, IBM Linux Technology Center, fubar@us.ibm.com



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