drm/amd/display: Implement bounds check for stream encoder creation in DCN401

Overview

In the Linux kernel, the following vulnerability has been resolved:

drm/amd/display: Implement bounds check for stream encoder creation in DCN401

'stream_enc_regs' array is an array of dcn10_stream_enc_registers structures. The array is initialized with four elements, corresponding to the four calls to stream_enc_regs() in the array initializer. This means that valid indices for this array are 0, 1, 2, and 3.

The error message 'stream_enc_regs' 4 <= 5 below, is indicating that there is an attempt to access this array with an index of 5, which is out of bounds. This could lead to undefined behavior

Here, eng_id is used as an index to access the stream_enc_regs array. If eng_id is 5, this would result in an out-of-bounds access on the stream_enc_regs array.

Thus fixing Buffer overflow error in dcn401_stream_encoder_create

Found by smatch: drivers/gpu/drm/amd/amdgpu/../display/dc/resource/dcn401/dcn401_resource.c:1209 dcn401_stream_encoder_create() error: buffer overflow 'stream_enc_regs' 4 <= 5

Affected

• Linux >= 4562236b3bc0a28aeb6ee93b2d8a849a4c4e1c7c < 00872dcc2a3e4a42155c2f3b7f21952a62301035
• Linux >= 4562236b3bc0a28aeb6ee93b2d8a849a4c4e1c7c < b219b46ad42df1dea9258788bcfea37181f3ccb2
• Linux >= 4562236b3bc0a28aeb6ee93b2d8a849a4c4e1c7c < bdf606810210e8e07a0cdf1af3c467291363b295
• Linux 4.15

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.