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From: Kees Cook <keescook@chromium.org>
To: Alex Deucher <alexander.deucher@amd.com>
Cc: "Kees Cook" <keescook@chromium.org>,
	"Harry Wentland" <harry.wentland@amd.com>,
	"Leo Li" <sunpeng.li@amd.com>,
	"Christian König" <christian.koenig@amd.com>,
	"David Airlie" <airlied@linux.ie>,
	"Daniel Vetter" <daniel@ffwll.ch>,
	"Martin Tsai" <martin.tsai@amd.com>,
	"Bindu Ramamurthy" <bindu.r@amd.com>,
	"Wenjing Liu" <wenjing.liu@amd.com>,
	"Daniel Wheeler" <daniel.wheeler@amd.com>,
	"Anson Jacob" <Anson.Jacob@amd.com>,
	"Nicholas Kazlauskas" <nicholas.kazlauskas@amd.com>,
	linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org,
	dri-devel@lists.freedesktop.org
Subject: [PATCH] drm/amd/display: Avoid HDCP over-read and corruption
Date: Fri, 28 May 2021 10:53:54 -0700	[thread overview]
Message-ID: <20210528175354.790719-1-keescook@chromium.org> (raw)

Instead of reading the desired 5 bytes of the actual target field,
the code was reading 8. This could result in a corrupted value if the
trailing 3 bytes were non-zero, so instead use an appropriately sized
and zero-initialized bounce buffer, and read only 5 bytes before casting
to u64.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/gpu/drm/amd/display/modules/hdcp/hdcp1_execution.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/modules/hdcp/hdcp1_execution.c b/drivers/gpu/drm/amd/display/modules/hdcp/hdcp1_execution.c
index 2cbd931363bd..6d26d9c63ab2 100644
--- a/drivers/gpu/drm/amd/display/modules/hdcp/hdcp1_execution.c
+++ b/drivers/gpu/drm/amd/display/modules/hdcp/hdcp1_execution.c
@@ -29,8 +29,10 @@ static inline enum mod_hdcp_status validate_bksv(struct mod_hdcp *hdcp)
 {
 	uint64_t n = 0;
 	uint8_t count = 0;
+	u8 bksv[sizeof(n)] = { };
 
-	memcpy(&n, hdcp->auth.msg.hdcp1.bksv, sizeof(uint64_t));
+	memcpy(bksv, hdcp->auth.msg.hdcp1.bksv, sizeof(hdcp->auth.msg.hdcp1.bksv));
+	n = *(uint64_t *)bksv;
 
 	while (n) {
 		count++;
-- 
2.25.1


WARNING: multiple messages have this Message-ID (diff)
From: Kees Cook <keescook@chromium.org>
To: Alex Deucher <alexander.deucher@amd.com>
Cc: "Martin Tsai" <martin.tsai@amd.com>,
	"Kees Cook" <keescook@chromium.org>,
	"Leo Li" <sunpeng.li@amd.com>,
	linux-kernel@vger.kernel.org, "Wenjing Liu" <wenjing.liu@amd.com>,
	"Anson Jacob" <Anson.Jacob@amd.com>,
	amd-gfx@lists.freedesktop.org,
	"Nicholas Kazlauskas" <nicholas.kazlauskas@amd.com>,
	"David Airlie" <airlied@linux.ie>,
	"Daniel Wheeler" <daniel.wheeler@amd.com>,
	dri-devel@lists.freedesktop.org,
	"Christian König" <christian.koenig@amd.com>,
	"Bindu Ramamurthy" <bindu.r@amd.com>
Subject: [PATCH] drm/amd/display: Avoid HDCP over-read and corruption
Date: Fri, 28 May 2021 10:53:54 -0700	[thread overview]
Message-ID: <20210528175354.790719-1-keescook@chromium.org> (raw)

Instead of reading the desired 5 bytes of the actual target field,
the code was reading 8. This could result in a corrupted value if the
trailing 3 bytes were non-zero, so instead use an appropriately sized
and zero-initialized bounce buffer, and read only 5 bytes before casting
to u64.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/gpu/drm/amd/display/modules/hdcp/hdcp1_execution.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/modules/hdcp/hdcp1_execution.c b/drivers/gpu/drm/amd/display/modules/hdcp/hdcp1_execution.c
index 2cbd931363bd..6d26d9c63ab2 100644
--- a/drivers/gpu/drm/amd/display/modules/hdcp/hdcp1_execution.c
+++ b/drivers/gpu/drm/amd/display/modules/hdcp/hdcp1_execution.c
@@ -29,8 +29,10 @@ static inline enum mod_hdcp_status validate_bksv(struct mod_hdcp *hdcp)
 {
 	uint64_t n = 0;
 	uint8_t count = 0;
+	u8 bksv[sizeof(n)] = { };
 
-	memcpy(&n, hdcp->auth.msg.hdcp1.bksv, sizeof(uint64_t));
+	memcpy(bksv, hdcp->auth.msg.hdcp1.bksv, sizeof(hdcp->auth.msg.hdcp1.bksv));
+	n = *(uint64_t *)bksv;
 
 	while (n) {
 		count++;
-- 
2.25.1


WARNING: multiple messages have this Message-ID (diff)
From: Kees Cook <keescook@chromium.org>
To: Alex Deucher <alexander.deucher@amd.com>
Cc: "Martin Tsai" <martin.tsai@amd.com>,
	"Kees Cook" <keescook@chromium.org>,
	"Leo Li" <sunpeng.li@amd.com>,
	linux-kernel@vger.kernel.org, "Wenjing Liu" <wenjing.liu@amd.com>,
	"Anson Jacob" <Anson.Jacob@amd.com>,
	amd-gfx@lists.freedesktop.org,
	"Nicholas Kazlauskas" <nicholas.kazlauskas@amd.com>,
	"David Airlie" <airlied@linux.ie>,
	"Daniel Wheeler" <daniel.wheeler@amd.com>,
	dri-devel@lists.freedesktop.org,
	"Daniel Vetter" <daniel@ffwll.ch>,
	"Harry Wentland" <harry.wentland@amd.com>,
	"Christian König" <christian.koenig@amd.com>,
	"Bindu Ramamurthy" <bindu.r@amd.com>
Subject: [PATCH] drm/amd/display: Avoid HDCP over-read and corruption
Date: Fri, 28 May 2021 10:53:54 -0700	[thread overview]
Message-ID: <20210528175354.790719-1-keescook@chromium.org> (raw)

Instead of reading the desired 5 bytes of the actual target field,
the code was reading 8. This could result in a corrupted value if the
trailing 3 bytes were non-zero, so instead use an appropriately sized
and zero-initialized bounce buffer, and read only 5 bytes before casting
to u64.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/gpu/drm/amd/display/modules/hdcp/hdcp1_execution.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/modules/hdcp/hdcp1_execution.c b/drivers/gpu/drm/amd/display/modules/hdcp/hdcp1_execution.c
index 2cbd931363bd..6d26d9c63ab2 100644
--- a/drivers/gpu/drm/amd/display/modules/hdcp/hdcp1_execution.c
+++ b/drivers/gpu/drm/amd/display/modules/hdcp/hdcp1_execution.c
@@ -29,8 +29,10 @@ static inline enum mod_hdcp_status validate_bksv(struct mod_hdcp *hdcp)
 {
 	uint64_t n = 0;
 	uint8_t count = 0;
+	u8 bksv[sizeof(n)] = { };
 
-	memcpy(&n, hdcp->auth.msg.hdcp1.bksv, sizeof(uint64_t));
+	memcpy(bksv, hdcp->auth.msg.hdcp1.bksv, sizeof(hdcp->auth.msg.hdcp1.bksv));
+	n = *(uint64_t *)bksv;
 
 	while (n) {
 		count++;
-- 
2.25.1

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

             reply	other threads:[~2021-05-28 17:55 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-28 17:53 Kees Cook [this message]
2021-05-28 17:53 ` [PATCH] drm/amd/display: Avoid HDCP over-read and corruption Kees Cook
2021-05-28 17:53 ` Kees Cook
2021-06-02  2:06 ` Alex Deucher
2021-06-02  2:06   ` Alex Deucher
2021-06-02  2:06   ` Alex Deucher

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