linux-kernel - [PATCH AUTOSEL 4.19 16/32] drm/amdgpu: fix a potential information leaking bug

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Message-Id: <20190806213522.19859-16-sashal@kernel.org>
Date:   Tue,  6 Aug 2019 17:35:04 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Wang Xiayang <xywang.sjtu@...u.edu.cn>,
        Chunming Zhou <david1.zhou@....com>,
        Christian König <christian.koenig@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Sasha Levin <sashal@...nel.org>, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 4.19 16/32] drm/amdgpu: fix a potential information leaking bug

From: Wang Xiayang <xywang.sjtu@...u.edu.cn>

[ Upstream commit 929e571c04c285861e0bb049a396a2bdaea63282 ]

Coccinelle reports a path that the array "data" is never initialized.
The path skips the checks in the conditional branches when either
of callback functions, read_wave_vgprs and read_wave_sgprs, is not
registered. Later, the uninitialized "data" array is read
in the while-loop below and passed to put_user().

Fix the path by allocating the array with kcalloc().

The patch is simplier than adding a fall-back branch that explicitly
calls memset(data, 0, ...). Also it does not need the multiplication
1024*sizeof(*data) as the size parameter for memset() though there is
no risk of integer overflow.

Signed-off-by: Wang Xiayang <xywang.sjtu@...u.edu.cn>
Reviewed-by: Chunming Zhou <david1.zhou@....com>
Reviewed-by: Christian König <christian.koenig@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
index f5fb93795a69a..65cecfdd9b454 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
@@ -707,7 +707,7 @@ static ssize_t amdgpu_debugfs_gpr_read(struct file *f, char __user *buf,
 	thread = (*pos & GENMASK_ULL(59, 52)) >> 52;
 	bank = (*pos & GENMASK_ULL(61, 60)) >> 60;
 
-	data = kmalloc_array(1024, sizeof(*data), GFP_KERNEL);
+	data = kcalloc(1024, sizeof(*data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;
 
-- 
2.20.1