4.19-stable review patch. If anyone has any objections, please let me know.
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From: Mario Limonciello mario.limonciello@amd.com
commit bf58f03931fdcf7b3c45cb76ac13244477a60f44 upstream.
If a BIOS provides bad data in response to an ATIF method call this causes a NULL pointer dereference in the caller.
``` ? show_regs (arch/x86/kernel/dumpstack.c:478 (discriminator 1)) ? __die (arch/x86/kernel/dumpstack.c:423 arch/x86/kernel/dumpstack.c:434) ? page_fault_oops (arch/x86/mm/fault.c:544 (discriminator 2) arch/x86/mm/fault.c:705 (discriminator 2)) ? do_user_addr_fault (arch/x86/mm/fault.c:440 (discriminator 1) arch/x86/mm/fault.c:1232 (discriminator 1)) ? acpi_ut_update_object_reference (drivers/acpi/acpica/utdelete.c:642) ? exc_page_fault (arch/x86/mm/fault.c:1542) ? asm_exc_page_fault (./arch/x86/include/asm/idtentry.h:623) ? amdgpu_atif_query_backlight_caps.constprop.0 (drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c:387 (discriminator 2)) amdgpu ? amdgpu_atif_query_backlight_caps.constprop.0 (drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c:386 (discriminator 1)) amdgpu ```
It has been encountered on at least one system, so guard for it.
Fixes: d38ceaf99ed0 ("drm/amdgpu: add core driver (v4)") Acked-by: Alex Deucher alexander.deucher@amd.com Signed-off-by: Mario Limonciello mario.limonciello@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com (cherry picked from commit c9b7c809b89f24e9372a4e7f02d64c950b07fdee) Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c @@ -90,6 +90,7 @@ static union acpi_object *amdgpu_atif_ca struct acpi_buffer *params) { acpi_status status; + union acpi_object *obj; union acpi_object atif_arg_elements[2]; struct acpi_object_list atif_arg; struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL }; @@ -112,16 +113,24 @@ static union acpi_object *amdgpu_atif_ca
status = acpi_evaluate_object(atif->handle, NULL, &atif_arg, &buffer); + obj = (union acpi_object *)buffer.pointer;
- /* Fail only if calling the method fails and ATIF is supported */ + /* Fail if calling the method fails and ATIF is supported */ if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) { DRM_DEBUG_DRIVER("failed to evaluate ATIF got %s\n", acpi_format_exception(status)); - kfree(buffer.pointer); + kfree(obj); return NULL; }
- return buffer.pointer; + if (obj->type != ACPI_TYPE_BUFFER) { + DRM_DEBUG_DRIVER("bad object returned from ATIF: %d\n", + obj->type); + kfree(obj); + return NULL; + } + + return obj; }
/**