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drm/amd/display: Fix the uninitialized variable in enable_stream_features()

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commit 0726ed3065eeb910f9cea0c933bc021a848e00b3 upstream.

In function enable_stream_features(), the variable "old_downspread.raw"
could be uninitialized if core_link_read_dpcd() fails, however, it is
used in the later if statement, and further, core_link_write_dpcd()
may write random value, which is potentially unsafe.

Fixes: 6016cd9dba0f ("drm/amd/display: add helper for enabling mst stream features")
Cc: stable@vger.kernel.org
Signed-off-by: Yizhuo Zhai <yzhai003@ucr.edu>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Yizhuo Zhai 2021-12-17 20:22:23 -08:00 committed by Greg Kroah-Hartman
parent 2de6ce5836
commit 3bf997ec29
1 changed files with 2 additions and 0 deletions
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2
drivers/gpu/drm/amd/display/dc/core/dc_link.c
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@ -1696,6 +1696,8 @@ static void enable_stream_features(struct pipe_ctx *pipe_ctx)
union down_spread_ctrl old_downspread;
union down_spread_ctrl new_downspread;
memset(&old_downspread, 0, sizeof(old_downspread));
core_link_read_dpcd(link, DP_DOWNSPREAD_CTRL,
&old_downspread.raw, sizeof(old_downspread));