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    Subject[PATCH 5.4 37/70] net: qlogic: qlcnic: Fix a NULL pointer dereference in qlcnic_83xx_add_rings()
    Date
    From: Zhou Qingyang <zhou1615@umn.edu>

    commit e2dabc4f7e7b60299c20a36d6a7b24ed9bf8e572 upstream.

    In qlcnic_83xx_add_rings(), the indirect function of
    ahw->hw_ops->alloc_mbx_args will be called to allocate memory for
    cmd.req.arg, and there is a dereference of it in qlcnic_83xx_add_rings(),
    which could lead to a NULL pointer dereference on failure of the
    indirect function like qlcnic_83xx_alloc_mbx_args().

    Fix this bug by adding a check of alloc_mbx_args(), this patch
    imitates the logic of mbx_cmd()'s failure handling.

    This bug was found by a static analyzer. The analysis employs
    differential checking to identify inconsistent security operations
    (e.g., checks or kfrees) between two code paths and confirms that the
    inconsistent operations are not recovered in the current function or
    the callers, so they constitute bugs.

    Note that, as a bug found by static analysis, it can be a false
    positive or hard to trigger. Multiple researchers have cross-reviewed
    the bug.

    Builds with CONFIG_QLCNIC=m show no new warnings, and our
    static analyzer no longer warns about this code.

    Fixes: 7f9664525f9c ("qlcnic: 83xx memory map and HW access routine")
    Signed-off-by: Zhou Qingyang <zhou1615@umn.edu>
    Link: https://lore.kernel.org/r/20211130110848.109026-1-zhou1615@umn.edu
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_hw.c | 10 ++++++++--
    1 file changed, 8 insertions(+), 2 deletions(-)

    --- a/drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_hw.c
    +++ b/drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_hw.c
    @@ -1079,8 +1079,14 @@ static int qlcnic_83xx_add_rings(struct
    sds_mbx_size = sizeof(struct qlcnic_sds_mbx);
    context_id = recv_ctx->context_id;
    num_sds = adapter->drv_sds_rings - QLCNIC_MAX_SDS_RINGS;
    - ahw->hw_ops->alloc_mbx_args(&cmd, adapter,
    - QLCNIC_CMD_ADD_RCV_RINGS);
    + err = ahw->hw_ops->alloc_mbx_args(&cmd, adapter,
    + QLCNIC_CMD_ADD_RCV_RINGS);
    + if (err) {
    + dev_err(&adapter->pdev->dev,
    + "Failed to alloc mbx args %d\n", err);
    + return err;
    + }
    +
    cmd.req.arg[1] = 0 | (num_sds << 8) | (context_id << 16);

    /* set up status rings, mbx 2-81 */

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