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From:   Sasha Levin <sashal@kernel.org>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     Lu Yao <yaolu@kylinos.cn>,
        =?UTF-8?q?Christian=20K=C3=B6nig?= <christian.koenig@amd.com>,
        Alex Deucher <alexander.deucher@amd.com>,
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        Hawking.Zhang@amd.com, srinivasan.shanmugam@amd.com,
        dan.carpenter@linaro.org, suhui@nfschina.com,
        andrealmeid@igalia.com, tom.stdenis@amd.com, le.ma@amd.com,
        amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org
Subject: [PATCH AUTOSEL 6.6 26/32] drm/amdgpu: Fix cat debugfs amdgpu_regs_didt causes kernel null pointer
Date:   Mon,  4 Dec 2023 15:32:46 -0500
Message-ID: <20231204203317.2092321-26-sashal@kernel.org>
In-Reply-To: <20231204203317.2092321-1-sashal@kernel.org>
References: <20231204203317.2092321-1-sashal@kernel.org>
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From: Lu Yao <yaolu@kylinos.cn>

[ Upstream commit 2161e09cd05a50d80736fe397145340d2e8f6c05 ]

For 'AMDGPU_FAMILY_SI' family cards, in 'si_common_early_init' func, init
'didt_rreg' and 'didt_wreg' to 'NULL'. But in func
'amdgpu_debugfs_regs_didt_read/write', using 'RREG32_DIDT' 'WREG32_DIDT'
lacks of relevant judgment. And other 'amdgpu_ip_block_version' that use
these two definitions won't be added for 'AMDGPU_FAMILY_SI'.

So, add null pointer judgment before calling.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Lu Yao <yaolu@kylinos.cn>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
index 05405da51e7a2..3f2126f99923e 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
@@ -638,6 +638,9 @@ static ssize_t amdgpu_debugfs_regs_didt_read(struct file *f, char __user *buf,
 	if (size & 0x3 || *pos & 0x3)
 		return -EINVAL;
 
+	if (!adev->didt_rreg)
+		return -EOPNOTSUPP;
+
 	r = pm_runtime_get_sync(adev_to_drm(adev)->dev);
 	if (r < 0) {
 		pm_runtime_put_autosuspend(adev_to_drm(adev)->dev);
@@ -694,6 +697,9 @@ static ssize_t amdgpu_debugfs_regs_didt_write(struct file *f, const char __user
 	if (size & 0x3 || *pos & 0x3)
 		return -EINVAL;
 
+	if (!adev->didt_wreg)
+		return -EOPNOTSUPP;
+
 	r = pm_runtime_get_sync(adev_to_drm(adev)->dev);
 	if (r < 0) {
 		pm_runtime_put_autosuspend(adev_to_drm(adev)->dev);
-- 
2.42.0