[PATCH] soc/tegra: fuse: Do not use fuse data as entropy source

[PATCH] soc/tegra: fuse: Do not use fuse data as entropy source

[Kartik Rajput]

Fuse values are static and device-unique but not secret. Using them as an
entropy source weakens the overall randomness pool because the data is
constant and externally observable over the device’s lifetime.

Stop feeding fuse data into the kernel’s randomness subsystem.

Signed-off-by: Kartik Rajput <kkartik@nvidia.com>
---
 drivers/soc/tegra/fuse/fuse-tegra30.c | 24 ------------------------
 1 file changed, 24 deletions(-)

diff --git a/drivers/soc/tegra/fuse/fuse-tegra30.c b/drivers/soc/tegra/fuse/fuse-tegra30.c
index 524fa1b0cd3d..2fad8b13a3b9 100644
--- a/drivers/soc/tegra/fuse/fuse-tegra30.c
+++ b/drivers/soc/tegra/fuse/fuse-tegra30.c
@@ -64,28 +64,6 @@ static u32 tegra30_fuse_read(struct tegra_fuse *fuse, unsigned int offset)
 	return value;
 }
 
-static void __init tegra30_fuse_add_randomness(void)
-{
-	u32 randomness[12];
-
-	randomness[0] = tegra_sku_info.sku_id;
-	randomness[1] = tegra_read_straps();
-	randomness[2] = tegra_read_chipid();
-	randomness[3] = tegra_sku_info.cpu_process_id << 16;
-	randomness[3] |= tegra_sku_info.soc_process_id;
-	randomness[4] = tegra_sku_info.cpu_speedo_id << 16;
-	randomness[4] |= tegra_sku_info.soc_speedo_id;
-	randomness[5] = tegra_fuse_read_early(FUSE_VENDOR_CODE);
-	randomness[6] = tegra_fuse_read_early(FUSE_FAB_CODE);
-	randomness[7] = tegra_fuse_read_early(FUSE_LOT_CODE_0);
-	randomness[8] = tegra_fuse_read_early(FUSE_LOT_CODE_1);
-	randomness[9] = tegra_fuse_read_early(FUSE_WAFER_ID);
-	randomness[10] = tegra_fuse_read_early(FUSE_X_COORDINATE);
-	randomness[11] = tegra_fuse_read_early(FUSE_Y_COORDINATE);
-
-	add_device_randomness(randomness, sizeof(randomness));
-}
-
 static void __init tegra30_fuse_init(struct tegra_fuse *fuse)
 {
 	fuse->read_early = tegra30_fuse_read_early;
@@ -95,8 +73,6 @@ static void __init tegra30_fuse_init(struct tegra_fuse *fuse)
 
 	if (fuse->soc->speedo_init)
 		fuse->soc->speedo_init(&tegra_sku_info);
-
-	tegra30_fuse_add_randomness();
 }
 #endif
 
-- 
2.43.0