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    Subject[PATCH 4.19 39/85] drm/amdgpu: fix a potential information leaking bug
    Date
    [ 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@sjtu.edu.cn>
    Reviewed-by: Chunming Zhou <david1.zhou@amd.com>
    Reviewed-by: Christian König <christian.koenig@amd.com>
    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 | 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


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