From: =?UTF-8?q?Ernst=20Sj=C3=B6strand?= <ernstp@gmail.com>
Date: Sun, 19 Nov 2017 18:52:44 +0100
Subject: drm/amd/amdgpu: Fix missing null check in atombios_i2c.c
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Git-commit: 7d0331007ab4bea446cf3d173410c3179b12e2ff
Patch-mainline: v4.16-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

Reported by smatch:
amdgpu_atombios_i2c_process_i2c_ch() error: we previously assumed 'buf' could be null

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Ernst Sjöstrand <ernstp@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/amd/amdgpu/atombios_i2c.c |   11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/amd/amdgpu/atombios_i2c.c
+++ b/drivers/gpu/drm/amd/amdgpu/atombios_i2c.c
@@ -65,8 +65,15 @@ static int amdgpu_atombios_i2c_process_i
 			args.ucRegIndex = buf[0];
 		if (num)
 			num--;
-		if (num)
-			memcpy(&out, &buf[1], num);
+		if (num) {
+			if (buf) {
+				memcpy(&out, &buf[1], num);
+			} else {
+				DRM_ERROR("hw i2c: missing buf with num > 1\n");
+				r = -EINVAL;
+				goto done;
+			}
+		}
 		args.lpI2CDataOut = cpu_to_le16(out);
 	} else {
 		if (num > ATOM_MAX_HW_I2C_READ) {