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Thu, 08 Jan 2026 12:40:27 -0800 (PST) Received: from DESKTOP-BKIPFGN ([45.43.86.16]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-59b7b24d929sm451392e87.54.2026.01.08.12.40.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 08 Jan 2026 12:40:26 -0800 (PST) From: Kery Qi To: harry.wentland@amd.com Cc: linux-kernel@vger.kernel.org, Kery Qi Subject: [PATCH] drm/amd/display: dce110: fix NULL deref in dce110_set_backlight_level() Date: Fri, 9 Jan 2026 04:40:19 +0800 Message-ID: <20260108204019.1870-1-qikeyu2017@gmail.com> X-Mailer: git-send-email 2.50.1.windows.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" dce110_set_backlight_level() computes controller_id from pipe_ctx->stream_res.tg->inst before validating that tg is present. pipe_ctx->stream_res.tg may be NULL on some paths, which can lead to a NULL pointer dereference (oops/DoS) when setting backlight. Fix this by requiring tg to be present before accessing tg->inst. Also check abm->funcs before dereferencing function pointers. Fixes: 4b0e95d1838f ("drm/amd/display: Add set backlight to hw sequencer.") Signed-off-by: Kery Qi --- drivers/gpu/drm/amd/display/dc/hwss/dce110/dce110_hwseq.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/amd/display/dc/hwss/dce110/dce110_hwseq.c b/dr= ivers/gpu/drm/amd/display/dc/hwss/dce110/dce110_hwseq.c index 0cdd8c74abdf..6177bc67ea9c 100644 --- a/drivers/gpu/drm/amd/display/dc/hwss/dce110/dce110_hwseq.c +++ b/drivers/gpu/drm/amd/display/dc/hwss/dce110/dce110_hwseq.c @@ -3263,10 +3263,15 @@ bool dce110_set_backlight_level(struct pipe_ctx *pi= pe_ctx, struct panel_cntl *panel_cntl =3D link->panel_cntl; struct dmcu *dmcu =3D dc->res_pool->dmcu; bool fw_set_brightness =3D true; + struct timing_generator *tg =3D pipe_ctx->stream_res.tg; + + if (!tg) + return false; + /* DMCU -1 for all controller id values, * therefore +1 here */ - uint32_t controller_id =3D pipe_ctx->stream_res.tg->inst + 1; + uint32_t controller_id =3D tg->inst + 1; =20 if (abm =3D=3D NULL || panel_cntl =3D=3D NULL || (abm->funcs->set_backlig= ht_level_pwm =3D=3D NULL)) return false; --=20 2.34.1