From: Ard Biesheuvel <ardb@kernel.org>
To: linux-efi@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org,
Ard Biesheuvel <ardb@kernel.org>,
stable@vger.kernel.org
Subject: [PATCH v3 4/4] efi/libstub: arm64: Double check image alignment at entry
Date: Mon, 26 Jul 2021 16:51:56 +0200 [thread overview]
Message-ID: <20210726145156.12006-5-ardb@kernel.org> (raw)
In-Reply-To: <20210726145156.12006-1-ardb@kernel.org>
On arm64, the stub only moves the kernel image around in memory if
needed, which is typically only for KASLR, given that relocatable
kernels (which is the default) can run from any 64k aligned address,
which is also the minimum alignment communicated to EFI via the PE/COFF
header.
Unfortunately, some loaders appear to ignore this header, and load the
kernel at some arbitrary offset in memory. We can deal with this, but
let's check for this condition anyway, so non-compliant code can be
spotted and fixed.
Cc: <stable@vger.kernel.org> # v5.10+
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
drivers/firmware/efi/libstub/arm64-stub.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/firmware/efi/libstub/arm64-stub.c b/drivers/firmware/efi/libstub/arm64-stub.c
index 010564f8bbc4..2363fee9211c 100644
--- a/drivers/firmware/efi/libstub/arm64-stub.c
+++ b/drivers/firmware/efi/libstub/arm64-stub.c
@@ -119,6 +119,10 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
if (image->image_base != _text)
efi_err("FIRMWARE BUG: efi_loaded_image_t::image_base has bogus value\n");
+ if (!IS_ALIGNED((u64)_text, EFI_KIMG_ALIGN))
+ efi_err("FIRMWARE BUG: kernel image not aligned on %ldk boundary\n",
+ EFI_KIMG_ALIGN >> 10);
+
kernel_size = _edata - _text;
kernel_memsize = kernel_size + (_end - _edata);
*reserve_size = kernel_memsize;
--
2.20.1
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next prev parent reply other threads:[~2021-07-26 14:55 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-26 14:51 [PATCH v3 0/4] efi/arm64: work around Image placement issues Ard Biesheuvel
2021-07-26 14:51 ` [PATCH v3 1/4] efi/libstub: arm64: Force Image reallocation if BSS was not reserved Ard Biesheuvel
2021-07-26 14:51 ` [PATCH v3 2/4] efi/libstub: arm64: Relax 2M alignment again for relocatable kernels Ard Biesheuvel
2021-07-26 14:51 ` [PATCH v3 3/4] efi/libstub: arm64: Warn when efi_random_alloc() fails Ard Biesheuvel
2021-07-26 14:51 ` Ard Biesheuvel [this message]
2021-08-02 11:26 ` [PATCH v3 0/4] efi/arm64: work around Image placement issues Benjamin Herrenschmidt
2021-08-02 12:03 ` Ard Biesheuvel
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