linux-kernel - [PATCH 2/2] drm/radeon: Avoid power table parsing memory leaks

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Message-Id: <20210503050608.2158996-3-keescook@chromium.org>
Date:   Sun,  2 May 2021 22:06:08 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Alex Deucher <alexander.deucher@....com>
Cc:     Kees Cook <keescook@...omium.org>,
        Christian König <christian.koenig@....com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        "Erhard F." <erhard_f@...lbox.org>, linux-kernel@...r.kernel.org,
        amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org
Subject: [PATCH 2/2] drm/radeon: Avoid power table parsing memory leaks

Avoid leaving a hanging pre-allocated clock_info if last mode is
invalid, and avoid heap corruption if no valid modes are found.

Fixes: 6991b8f2a319 ("drm/radeon/kms: fix segfault in pm rework")
Signed-off-by: Kees Cook <keescook@...omium.org>
---
 drivers/gpu/drm/radeon/radeon_atombios.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/radeon/radeon_atombios.c b/drivers/gpu/drm/radeon/radeon_atombios.c
index f9f4efa1738c..28c4413f4dc8 100644
--- a/drivers/gpu/drm/radeon/radeon_atombios.c
+++ b/drivers/gpu/drm/radeon/radeon_atombios.c
@@ -2120,11 +2120,14 @@ static int radeon_atombios_parse_power_table_1_3(struct radeon_device *rdev)
 		return state_index;
 	/* last mode is usually default, array is low to high */
 	for (i = 0; i < num_modes; i++) {
-		rdev->pm.power_state[state_index].clock_info =
-			kcalloc(1, sizeof(struct radeon_pm_clock_info),
-				GFP_KERNEL);
+		/* avoid memory leaks from invalid modes or unknown frev. */
+		if (!rdev->pm.power_state[state_index].clock_info) {
+			rdev->pm.power_state[state_index].clock_info =
+				kzalloc(sizeof(struct radeon_pm_clock_info),
+					GFP_KERNEL);
+		}
 		if (!rdev->pm.power_state[state_index].clock_info)
-			return state_index;
+			goto out;
 		rdev->pm.power_state[state_index].num_clock_modes = 1;
 		rdev->pm.power_state[state_index].clock_info[0].voltage.type = VOLTAGE_NONE;
 		switch (frev) {
@@ -2243,8 +2246,15 @@ static int radeon_atombios_parse_power_table_1_3(struct radeon_device *rdev)
 			break;
 		}
 	}
+out:
+	/* free any unused clock_info allocation. */
+	if (state_index && state_index < num_modes) {
+		kfree(rdev->pm.power_state[state_index].clock_info);
+		rdev->pm.power_state[state_index].clock_info = NULL;
+	}
+
 	/* last mode is usually default */
-	if (rdev->pm.default_power_state_index == -1) {
+	if (state_index && rdev->pm.default_power_state_index == -1) {
 		rdev->pm.power_state[state_index - 1].type =
 			POWER_STATE_TYPE_DEFAULT;
 		rdev->pm.default_power_state_index = state_index - 1;
-- 
2.25.1