From: Ard Biesheuvel <ardb@kernel.org>
To: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Yuntao Wang <ytcoode@gmail.com>,
linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org,
"Borislav Petkov (AMD)" <bp@alien8.de>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Ingo Molnar <mingo@kernel.org>,
Dionna Glaze <dionnaglaze@google.com>,
Nikolay Borisov <nik.borisov@suse.com>
Subject: Re: [PATCH] x86/efistub: fix the missing KASLR_FLAG bit in boot_params->hdr.loadflags
Date: Tue, 2 Jan 2024 17:26:58 +0100 [thread overview]
Message-ID: <CAMj1kXELiSzz75EGJuYwvSURfjGmZaRLEQghvGVVc5JMN+Npow@mail.gmail.com> (raw)
In-Reply-To: <b2c4835d-0076-47f0-b0d1-792dc32cc305@amd.com>
On Tue, 2 Jan 2024 at 17:26, Tom Lendacky <thomas.lendacky@amd.com> wrote:
>
> On 1/2/24 09:29, Ard Biesheuvel wrote:
> > On Tue, 26 Dec 2023 at 15:03, Yuntao Wang <ytcoode@gmail.com> wrote:
> >>
> >> 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 kernel is booted via 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.
> >>
> >> Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
> >> ---
> >> drivers/firmware/efi/libstub/x86-stub.c | 5 ++++-
> >> 1 file changed, 4 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c
> >> index da9b7b8d0716..b0c68593ad40 100644
> >> --- a/drivers/firmware/efi/libstub/x86-stub.c
> >> +++ b/drivers/firmware/efi/libstub/x86-stub.c
> >> @@ -787,7 +787,10 @@ static efi_status_t efi_decompress_kernel(unsigned long *kernel_entry)
> >> efi_debug("AMI firmware v2.0 or older detected - disabling physical KASLR\n");
> >> seed[0] = 0;
> >> }
> >> - }
> >> +
> >> + boot_params_ptr->hdr.loadflags |= KASLR_FLAG;
> >> + } else
> >> + boot_params_ptr->hdr.loadflags &= ~KASLR_FLAG;
> >>
> >
> > Thanks for the fix.
>
> Does it need a Fixes: tag?
>
Yes, I've added that.
prev parent reply other threads:[~2024-01-02 16:27 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-26 14:02 [PATCH] x86/efistub: fix the missing KASLR_FLAG bit in boot_params->hdr.loadflags Yuntao Wang
2024-01-02 15:29 ` Ard Biesheuvel
2024-01-02 16:26 ` Tom Lendacky
2024-01-02 16:26 ` Ard Biesheuvel [this message]
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