linux-kernel - [PATCH AUTOSEL 4.9 02/12] drm/radeon: Initialize fences array entries in radeon_sa_bo_next

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Message-Id: <20220811161144.1543598-2-sashal@kernel.org>
Date:   Thu, 11 Aug 2022 12:11:28 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Xiaohui Zhang <xiaohuizhang@....edu.cn>,
        Alex Deucher <alexander.deucher@....com>,
        Sasha Levin <sashal@...nel.org>, christian.koenig@....com,
        Xinhui.Pan@....com, airlied@...ux.ie, daniel@...ll.ch,
        amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 4.9 02/12] drm/radeon: Initialize fences array entries in radeon_sa_bo_next_hole

From: Xiaohui Zhang <xiaohuizhang@....edu.cn>

[ Upstream commit 0381ac3ca2e727d4dfb7264d9416a8ba6bb6c18b ]

Similar to the handling of amdgpu_sa_bo_next_hole in commit 6a15f3ff19a8
("drm/amdgpu: Initialize fences array entries in amdgpu_sa_bo_next_hole"),
we thought a patch might be needed here as well.

The entries were only initialized once in radeon_sa_bo_new. If a fence
wasn't signalled yet in the first radeon_sa_bo_next_hole call, but then
got signalled before a later radeon_sa_bo_next_hole call, it could
destroy the fence but leave its pointer in the array, resulting in
use-after-free in radeon_sa_bo_new.

Signed-off-by: Xiaohui Zhang <xiaohuizhang@....edu.cn>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/radeon/radeon_sa.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/radeon/radeon_sa.c b/drivers/gpu/drm/radeon/radeon_sa.c
index 197b157b73d0..0cb6eeb77b5f 100644
--- a/drivers/gpu/drm/radeon/radeon_sa.c
+++ b/drivers/gpu/drm/radeon/radeon_sa.c
@@ -267,6 +267,8 @@ static bool radeon_sa_bo_next_hole(struct radeon_sa_manager *sa_manager,
 	for (i = 0; i < RADEON_NUM_RINGS; ++i) {
 		struct radeon_sa_bo *sa_bo;
 
+		fences[i] = NULL;
+
 		if (list_empty(&sa_manager->flist[i])) {
 			continue;
 		}
@@ -332,10 +334,8 @@ int radeon_sa_bo_new(struct radeon_device *rdev,
 
 	spin_lock(&sa_manager->wq.lock);
 	do {
-		for (i = 0; i < RADEON_NUM_RINGS; ++i) {
-			fences[i] = NULL;
+		for (i = 0; i < RADEON_NUM_RINGS; ++i)
 			tries[i] = 0;
-		}
 
 		do {
 			radeon_sa_bo_try_free(sa_manager);
-- 
2.35.1