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From: Wayne Lin <Wayne.Lin@amd.com>
To: <dri-devel@lists.freedesktop.org>, <amd-gfx@lists.freedesktop.org>
Cc: stable@vger.kernel.org, jerry.zuo@amd.com,
	Wayne Lin <Wayne.Lin@amd.com>,
	mikita.lipski@amd.com, harry.wentland@amd.com,
	Nicholas.Kazlauskas@amd.com
Subject: [PATCH] drm/dp_mst: Avoid NULL pointer dereference
Date: Thu, 26 Dec 2019 10:31:51 +0800	[thread overview]
Message-ID: <20191226023151.5448-1-Wayne.Lin@amd.com> (raw)

[Why]
Found kernel NULL pointer dereference under the below situation:

	src — HDMI_Monitor   src — HDMI_Monitor
e.g.:	    \            =>
	     MSTB — MSTB     (unplug) MSTB — MSTB

When display 1 HDMI and 2 DP daisy chain monitors, unplugging the dp
cable connected to source causes kernel NULL pointer dereference at
drm_dp_mst_atomic_check_bw_limit(). When calculating pbn_limit, if
branch is null, accessing "&branch->ports" causes the problem.

[How]
Judge branch is null or not at the beginning. If it is null, return 0.

Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
Cc: stable@vger.kernel.org
---
 drivers/gpu/drm/drm_dp_mst_topology.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 7d2d31eaf003..a6473e3ab448 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -4707,6 +4707,9 @@ int drm_dp_mst_atomic_check_bw_limit(struct drm_dp_mst_branch *branch,
 	struct drm_dp_vcpi_allocation *vcpi;
 	int pbn_limit = 0, pbn_used = 0;
 
+	if (!branch)
+		return 0;
+
 	list_for_each_entry(port, &branch->ports, next) {
 		if (port->mstb)
 			if (drm_dp_mst_atomic_check_bw_limit(port->mstb, mst_state))
-- 
2.17.1

_______________________________________________
amd-gfx mailing list
amd-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/amd-gfx

WARNING: multiple messages have this Message-ID (diff)
From: Wayne Lin <Wayne.Lin@amd.com>
To: <dri-devel@lists.freedesktop.org>, <amd-gfx@lists.freedesktop.org>
Cc: stable@vger.kernel.org, jerry.zuo@amd.com,
	Wayne Lin <Wayne.Lin@amd.com>,
	mikita.lipski@amd.com, Nicholas.Kazlauskas@amd.com
Subject: [PATCH] drm/dp_mst: Avoid NULL pointer dereference
Date: Thu, 26 Dec 2019 10:31:51 +0800	[thread overview]
Message-ID: <20191226023151.5448-1-Wayne.Lin@amd.com> (raw)

[Why]
Found kernel NULL pointer dereference under the below situation:

	src — HDMI_Monitor   src — HDMI_Monitor
e.g.:	    \            =>
	     MSTB — MSTB     (unplug) MSTB — MSTB

When display 1 HDMI and 2 DP daisy chain monitors, unplugging the dp
cable connected to source causes kernel NULL pointer dereference at
drm_dp_mst_atomic_check_bw_limit(). When calculating pbn_limit, if
branch is null, accessing "&branch->ports" causes the problem.

[How]
Judge branch is null or not at the beginning. If it is null, return 0.

Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
Cc: stable@vger.kernel.org
---
 drivers/gpu/drm/drm_dp_mst_topology.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 7d2d31eaf003..a6473e3ab448 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -4707,6 +4707,9 @@ int drm_dp_mst_atomic_check_bw_limit(struct drm_dp_mst_branch *branch,
 	struct drm_dp_vcpi_allocation *vcpi;
 	int pbn_limit = 0, pbn_used = 0;
 
+	if (!branch)
+		return 0;
+
 	list_for_each_entry(port, &branch->ports, next) {
 		if (port->mstb)
 			if (drm_dp_mst_atomic_check_bw_limit(port->mstb, mst_state))
-- 
2.17.1

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

WARNING: multiple messages have this Message-ID (diff)
From: Wayne Lin <Wayne.Lin@amd.com>
To: <dri-devel@lists.freedesktop.org>, <amd-gfx@lists.freedesktop.org>
Cc: <lyude@redhat.com>, <Nicholas.Kazlauskas@amd.com>,
	<harry.wentland@amd.com>, <mikita.lipski@amd.com>,
	<jerry.zuo@amd.com>, <stable@vger.kernel.org>,
	Wayne Lin <Wayne.Lin@amd.com>
Subject: [PATCH] drm/dp_mst: Avoid NULL pointer dereference
Date: Thu, 26 Dec 2019 10:31:51 +0800	[thread overview]
Message-ID: <20191226023151.5448-1-Wayne.Lin@amd.com> (raw)

[Why]
Found kernel NULL pointer dereference under the below situation:

	src — HDMI_Monitor   src — HDMI_Monitor
e.g.:	    \            =>
	     MSTB — MSTB     (unplug) MSTB — MSTB

When display 1 HDMI and 2 DP daisy chain monitors, unplugging the dp
cable connected to source causes kernel NULL pointer dereference at
drm_dp_mst_atomic_check_bw_limit(). When calculating pbn_limit, if
branch is null, accessing "&branch->ports" causes the problem.

[How]
Judge branch is null or not at the beginning. If it is null, return 0.

Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
Cc: stable@vger.kernel.org
---
 drivers/gpu/drm/drm_dp_mst_topology.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 7d2d31eaf003..a6473e3ab448 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -4707,6 +4707,9 @@ int drm_dp_mst_atomic_check_bw_limit(struct drm_dp_mst_branch *branch,
 	struct drm_dp_vcpi_allocation *vcpi;
 	int pbn_limit = 0, pbn_used = 0;
 
+	if (!branch)
+		return 0;
+
 	list_for_each_entry(port, &branch->ports, next) {
 		if (port->mstb)
 			if (drm_dp_mst_atomic_check_bw_limit(port->mstb, mst_state))
-- 
2.17.1


             reply	other threads:[~2019-12-26  2:33 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-26  2:31 Wayne Lin [this message]
2019-12-26  2:31 ` [PATCH] drm/dp_mst: Avoid NULL pointer dereference Wayne Lin
2019-12-26  2:31 ` Wayne Lin
2019-12-26 15:04 ` Lipski, Mikita
2019-12-26 15:04   ` Lipski, Mikita
2019-12-26 15:04   ` Lipski, Mikita
2020-01-03 20:35 ` Lyude Paul
2020-01-03 20:35   ` Lyude Paul
2020-01-03 20:35   ` Lyude Paul
2020-01-06  7:34   ` 回覆: " Lin, Wayne
2020-01-06  7:34     ` Lin, Wayne
2020-01-06  7:34     ` Lin, Wayne

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