[PATCH 4.14 76/91] drm/amdgpu: Fix buffer overflow in INFO ioctl

[Greg Kroah-Hartman]

From: Alex Deucher <alexander.deucher@xxxxxxx>

commit b5b97cab55eb71daba3283c8b1d2cce456d511a1 upstream.

The values for "se_num" and "sh_num" come from the user in the ioctl.
They can be in the 0-255 range but if they're more than
AMDGPU_GFX_MAX_SE (4) or AMDGPU_GFX_MAX_SH_PER_SE (2) then it results in
an out of bounds read.

Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Acked-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
@@ -502,8 +502,12 @@ static int amdgpu_info_ioctl(struct drm_
 		 * in the bitfields */
 		if (se_num == AMDGPU_INFO_MMR_SE_INDEX_MASK)
 			se_num = 0xffffffff;
+		else if (se_num >= AMDGPU_GFX_MAX_SE)
+			return -EINVAL;
 		if (sh_num == AMDGPU_INFO_MMR_SH_INDEX_MASK)
 			sh_num = 0xffffffff;
+		else if (sh_num >= AMDGPU_GFX_MAX_SH_PER_SE)
+			return -EINVAL;
 
 		if (info->read_mmr_reg.count > 128)
 			return -EINVAL;