efi: fix userspace infinite retry read efivars after EFI runtime services page fault

[ Upstream commit e006ac3003080177cf0b673441a4241f77aaecce ]

After [1][2], if we catch exceptions due to EFI runtime service, we will
clear EFI_RUNTIME_SERVICES bit to disable EFI runtime service, then the
subsequent routine which invoke the EFI runtime service should fail.

But the userspace cat efivars through /sys/firmware/efi/efivars/ will stuck
and infinite loop calling read() due to efivarfs_file_read() return -EINTR.

The -EINTR is converted from EFI_ABORTED by efi_status_to_err(), and is
an improper return value in this situation, so let virt_efi_xxx() return
EFI_DEVICE_ERROR and converted to -EIO to invoker.

Cc: <stable@vger.kernel.org>
Fixes: 758e32faf330 ("efi/x86: Handle page faults occurring while running EFI runtime services")
Fixes: 796d30f89b2f ("arm64: efi: Recover from synchronous exceptions occurring in firmware")
Signed-off-by: Ding Hui <dinghui@sangfor.com.cn>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/firmware/efi/runtime-wrappers.c b/drivers/firmware/efi/runtime-wrappers.c
index 136b9c7f9ac95090343414a13c4e736d4a5d3ccb..a6735f1a16d14452b549916f981bbbf521bd3d04 100644 (file)
--- a/drivers/firmware/efi/runtime-wrappers.c
+++ b/drivers/firmware/efi/runtime-wrappers.c
@@ -62,6 +62,7 @@ struct efi_runtime_work efi_rts_work;
                                                                        \
        if (!efi_enabled(EFI_RUNTIME_SERVICES)) {                       \
                pr_warn_once("EFI Runtime Services are disabled!\n");   \
+               efi_rts_work.status = EFI_DEVICE_ERROR;                 \
                goto exit;                                              \
        }                                                               \
                                                                        \