[PATCH 6.1 196/215] efi/x86: Fix the missing KASLR_FLAG bit in boot_params->hdr.loadflags

Greg Kroah-Hartman
2024-03-04T21:51:29Z

From: Ard Biesheuvel <ardb+git@google.com>

From: Yuntao Wang <ytcoode@gmail.com>

[ Commit 01638431c465741e071ab34acf3bef3c2570f878 upstream ]

When KASLR is enabled, the KASLR_FLAG bit in boot_params->hdr.loadflags
should be set to 1 to propagate KASLR status from compressed kernel to
kernel, just as the choose_random_location() function does.

Currently, when the kernel is booted via the EFI stub, the KASLR_FLAG
bit in boot_params->hdr.loadflags is not set, even though it should be.
This causes some functions, such as kernel_randomize_memory(), not to
execute as expected. Fix it.

Fixes: a1b87d54f4e4 ("x86/efistub: Avoid legacy decompressor when doing EFI boot")
Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
[ardb: drop 'else' branch clearing KASLR_FLAG]
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/firmware/efi/libstub/x86-stub.c | 2 ++
1 file changed, 2 insertions(+)

--- a/drivers/firmware/efi/libstub/x86-stub.c
+++ b/drivers/firmware/efi/libstub/x86-stub.c
@@ -781,6 +781,8 @@ static efi_status_t efi_decompress_kerne
efi_debug("AMI firmware v2.0 or older detected - disabling physical KASLR\n");
seed[0] = 0;
}
+
+ boot_params_ptr->hdr.loadflags |= KASLR_FLAG;
}

status = efi_random_alloc(alloc_size, CONFIG_PHYSICAL_ALIGN, &addr,