From: Jason Andryuk <jason.andryuk@amd.com>
To: Ard Biesheuvel <ardb+git@google.com>, <linux-kernel@vger.kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>, Juergen Gross <jgross@suse.com>,
"Boris Ostrovsky" <boris.ostrovsky@oracle.com>, <x86@kernel.org>,
<xen-devel@lists.xenproject.org>
Subject: Re: [PATCH v3 4/5] x86/xen: Avoid relocatable quantities in Xen ELF notes
Date: Wed, 9 Oct 2024 13:16:36 -0400 [thread overview]
Message-ID: <03b3647b-49f9-4a9a-be65-3170bde65730@amd.com> (raw)
In-Reply-To: <20241009160438.3884381-11-ardb+git@google.com>
On 2024-10-09 12:04, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb@kernel.org>
>
> Xen puts virtual and physical addresses into ELF notes that are treated
> by the linker as relocatable by default. Doing so is not only pointless,
> given that the ELF notes are only intended for consumption by Xen before
> the kernel boots. It is also a KASLR leak, given that the kernel's ELF
> notes are exposed via the world readable /sys/kernel/notes.
>
> So emit these constants in a way that prevents the linker from marking
> them as relocatable. This involves place-relative relocations (which
> subtract their own virtual address from the symbol value) and linker
> provided absolute symbols that add the address of the place to the
> desired value.
>
> Tested-by: Jason Andryuk <jason.andryuk@amd.com>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Jason Andryuk <jason.andryuk@amd.com>
Thanks,
Jason
next prev parent reply other threads:[~2024-10-09 17:16 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-09 16:04 [PATCH v3 0/5] x86/xen: Drop absolute references from startup code Ard Biesheuvel
2024-10-09 16:04 ` [PATCH v3 1/5] x86/pvh: Call C code via the kernel virtual mapping Ard Biesheuvel
2024-10-09 16:04 ` [PATCH v3 2/5] x86/pvh: Use correct size value in GDT descriptor Ard Biesheuvel
2024-10-09 16:04 ` [PATCH v3 3/5] x86/pvh: Omit needless clearing of phys_base Ard Biesheuvel
2024-10-09 16:04 ` [PATCH v3 4/5] x86/xen: Avoid relocatable quantities in Xen ELF notes Ard Biesheuvel
2024-10-09 17:16 ` Jason Andryuk [this message]
2024-10-09 16:04 ` [PATCH v3 5/5] x86/pvh: Avoid absolute symbol references in .head.text Ard Biesheuvel
2024-10-29 12:50 ` [PATCH v3 0/5] x86/xen: Drop absolute references from startup code Ard Biesheuvel
2024-10-29 12:54 ` Jürgen Groß
2024-10-30 13:48 ` Ard Biesheuvel
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