From: Huacai Chen <chenhuacai@kernel.org>
To: WANG Rui <r@hev.cc>
Cc: Ard Biesheuvel <ardb@kernel.org>, WANG Xuerui <kernel@xen0n.name>,
Ilias Apalodimas <ilias.apalodimas@linaro.org>,
Haiyong Sun <sunhaiyong@loongson.cn>,
Lisa Robinson <lisa@bytefly.space>,
loongarch@lists.linux.dev, linux-efi@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 0/3] LoongArch: Move KASLR to EFI stub to avoid initrd overlap
Date: Sat, 9 May 2026 22:10:40 +0800 [thread overview]
Message-ID: <CAAhV-H7yU4Vf6K+f164_QWBkvNn4MzyzFDrCXsOmS=NnA9YmqA@mail.gmail.com> (raw)
In-Reply-To: <20260429120300.1786210-1-r@hev.cc>
Applied, thanks.
Huacai
On Wed, Apr 29, 2026 at 8:03 PM WANG Rui <r@hev.cc> wrote:
>
> Changes since [v3]:
> * Minor cleanups based on review comments.
>
> Changes since [v2]:
> * Add a new patch to prevent initrd overlap during relocation.
> * Revert changes to the CONFIG_RANDOMIZE_BASE_MAX_OFFSET range.
>
> Changes since [v1]:
> * Drop the patch "LoongArch: Allow rdtime_h() and rdtime_l() in 64-bit builds".
> * Use random_get_entropy() instead of rdtime_l().
>
> This series addresses a potential overlap issue between the kernel
> image and the initrd when KASLR is enabled.
>
> In the normal boot flow, the bootloader is responsible for loading
> both vmlinux and the initrd, and it can guarantee that the two do
> not overlap in memory. However, this assumption only holds as long
> as neither image changes its location afterwards.
>
> The in-kernel KASLR implementation breaks that assumption. When the
> initrd is placed close to the kernel image, randomizing the kernel
> location at runtime may move it into the initrd region, leading to
> memory corruption early during boot.
>
> To fix this, this series moves the KASLR logic out of the kernel
> proper and into the EFI stub. With this change, the final placement
> of both the kernel image and the initrd is determined by the EFI
> memory allocator. This ensures that the two allocations are
> coordinated and cannot overlap.
>
> Functionally, the kernel still supports KASLR as before, but the
> randomization now happens before the kernel is entered, rather than
> during early kernel relocation.
>
> [v3]: https://lore.kernel.org/loongarch/20260429051318.1581350-1-r@hev.cc
> [v2]: https://lore.kernel.org/loongarch/20260428040159.1065822-1-r@hev.cc
> [v1]: https://lore.kernel.org/loongarch/20260427104721.47724-1-r@hev.cc
>
> WANG Rui (3):
> efi/loongarch: Randomize kernel preferred address for KASLR
> LoongArch: Skip relocation-time KASLR if it has already been applied
> LoongArch: Avoid initrd overlap during kernel relocation
>
> arch/loongarch/include/asm/efi.h | 4 +-
> arch/loongarch/kernel/relocate.c | 49 ++++++++++++++++++++++++
> drivers/firmware/efi/libstub/loongarch.c | 16 ++++++++
> 3 files changed, 68 insertions(+), 1 deletion(-)
>
> --
> 2.54.0
>
>
prev parent reply other threads:[~2026-05-09 14:10 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-29 12:02 [PATCH v4 0/3] LoongArch: Move KASLR to EFI stub to avoid initrd overlap WANG Rui
2026-04-29 12:02 ` [PATCH v4 1/3] efi/loongarch: Randomize kernel preferred address for KASLR WANG Rui
2026-04-29 12:02 ` [PATCH v4 2/3] LoongArch: Skip relocation-time KASLR if it has already been applied WANG Rui
2026-04-29 12:03 ` [PATCH v4 3/3] LoongArch: Avoid initrd overlap during kernel relocation WANG Rui
2026-05-09 14:10 ` Huacai Chen [this message]
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