drm/amdgpu: fix mc_data out-of-bounds read warning

timhuang-amd · smb49 · commit df45646b757c · 2024-09-27T11:57:47.000+02:00
BugLink: https://bugs.launchpad.net/bugs/2081279 [ Upstream commit 51dfc0a ] Clear warning that read mc_data[i-1] may out-of-bounds. Signed-off-by: Tim Huang <Tim.Huang@amd.com> Reviewed-by: Alex Deucher <alexander.deucher@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Koichiro Den <koichiro.den@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c
@@ -1475,6 +1475,8 @@ int amdgpu_atombios_init_mc_reg_table(struct amdgpu_device *adev,
 										(u32)le32_to_cpu(*((u32 *)reg_data + j));
 									j++;
 								} else if ((reg_table->mc_reg_address[i].pre_reg_data & LOW_NIBBLE_MASK) == DATA_EQU_PREV) {
+									if (i == 0)
+										continue;
 									reg_table->mc_reg_table_entry[num_ranges].mc_data[i] =
 										reg_table->mc_reg_table_entry[num_ranges].mc_data[i - 1];
 								}

Original file line number	Diff line number	Diff line change
`@@ -1475,6 +1475,8 @@ int amdgpu_atombios_init_mc_reg_table(struct amdgpu_device *adev,`
`1475`	`1475`	`(u32)le32_to_cpu(((u32 )reg_data + j));`
`1476`	`1476`	`j++;`
`1477`	`1477`	`} else if ((reg_table->mc_reg_address[i].pre_reg_data & LOW_NIBBLE_MASK) == DATA_EQU_PREV) {`
	`1478`	`+ if (i == 0)`
	`1479`	`+ continue;`
`1478`	`1480`	`reg_table->mc_reg_table_entry[num_ranges].mc_data[i] =`
`1479`	`1481`	`reg_table->mc_reg_table_entry[num_ranges].mc_data[i - 1];`
`1480`	`1482`	`}`