drm/amdgpu: Check for valid number of registers to read

[ Upstream commit 73d8e6c ]

Do not try to allocate any amount of memory requested by the user.
Instead limit it to 128 registers. Actually the longest series of
consecutive allowed registers are 48, mmGB_TILE_MODE0-31 and
mmGB_MACROTILE_MODE0-15 (0x2644-0x2673).

Bug: https://bugs.freedesktop.org/show_bug.cgi?id=111273
Signed-off-by: Trek <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>

Author: trek00

drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c

@@ -430,6 +430,9 @@ static int amdgpu_info_ioctl(struct drm_device *dev, void *data, struct drm_file
 		if (sh_num == AMDGPU_INFO_MMR_SH_INDEX_MASK)
 			sh_num = 0xffffffff;
 
+		if (info->read_mmr_reg.count > 128)
+			return -EINVAL;
+
 		regs = kmalloc_array(info->read_mmr_reg.count, sizeof(*regs), GFP_KERNEL);
 		if (!regs)
 			return -ENOMEM;