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    Subject[PATCH AUTOSEL 5.14 148/252] drm/display: fix possible null-pointer dereference in dcn10_set_clock()
    Date
    From: Tuo Li <islituo@gmail.com>

    [ Upstream commit 554594567b1fa3da74f88ec7b2dc83d000c58e98 ]

    The variable dc->clk_mgr is checked in:
    if (dc->clk_mgr && dc->clk_mgr->funcs->get_clock)

    This indicates dc->clk_mgr can be NULL.
    However, it is dereferenced in:
    if (!dc->clk_mgr->funcs->get_clock)

    To fix this null-pointer dereference, check dc->clk_mgr and the function
    pointer dc->clk_mgr->funcs->get_clock earlier, and return if one of them
    is NULL.

    Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
    Signed-off-by: Tuo Li <islituo@gmail.com>
    Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    .../gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c | 11 +++++------
    1 file changed, 5 insertions(+), 6 deletions(-)

    diff --git a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c
    index dee1ce5f9609..75fa4adcf5f4 100644
    --- a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c
    +++ b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c
    @@ -3628,13 +3628,12 @@ enum dc_status dcn10_set_clock(struct dc *dc,
    struct dc_clock_config clock_cfg = {0};
    struct dc_clocks *current_clocks = &context->bw_ctx.bw.dcn.clk;

    - if (dc->clk_mgr && dc->clk_mgr->funcs->get_clock)
    - dc->clk_mgr->funcs->get_clock(dc->clk_mgr,
    - context, clock_type, &clock_cfg);
    -
    - if (!dc->clk_mgr->funcs->get_clock)
    + if (!dc->clk_mgr || !dc->clk_mgr->funcs->get_clock)
    return DC_FAIL_UNSUPPORTED_1;

    + dc->clk_mgr->funcs->get_clock(dc->clk_mgr,
    + context, clock_type, &clock_cfg);
    +
    if (clk_khz > clock_cfg.max_clock_khz)
    return DC_FAIL_CLK_EXCEED_MAX;

    @@ -3652,7 +3651,7 @@ enum dc_status dcn10_set_clock(struct dc *dc,
    else
    return DC_ERROR_UNEXPECTED;

    - if (dc->clk_mgr && dc->clk_mgr->funcs->update_clocks)
    + if (dc->clk_mgr->funcs->update_clocks)
    dc->clk_mgr->funcs->update_clocks(dc->clk_mgr,
    context, true);
    return DC_OK;
    --
    2.30.2
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