git.ipfire.org Git - thirdparty/openembedded/openembedded-core-contrib.git/blob

   1 From d48ec5e1a5fb7907520dee71b1d94045486a0c29 Mon Sep 17 00:00:00 2001
   2 From: Alexander Kamensky <alexander.kamensky42@gmail.com>
   3 Date: Thu, 12 Nov 2020 12:56:46 -0800
   4 Subject: [PATCH] arm64: kexec: disabled check if kaslr-seed dtb property was
   5  wiped
   6
   7 Kexec when loading arm64 kernel checks if chosen/kaslr-seed dtb property is
   8 wiped. It's a good assertion to verify proper behavior of kernel. However,
   9 if bootloader creates and fills kaslr-seed property and kernel is not
  10 configured with CONFIG_RANDOMIZE_BASE then logic of reading and wiping
  11 kaslr-seed does not run. As a result kaslr-seed property is not zero and when
  12 kexec tries to load secondary kernel it fails with the following message:
  13
  14 setup_2nd_dtb: kaslr-seed is not wiped to 0.
  15 kexec: setup_2nd_dtb failed.
  16 kexec: load failed.
  17
  18 This was observed on Yocto Project on qemuarm64 machine with 5.8 kernel,
  19 qemu 5.1.0. Qemu created kaslr-seed property but kernel was not configured
  20 with CONFIG_RANDOMIZE_BASE.
  21
  22 Although check has some value, there is a use-case where it breaks kexec,
  23 this patch removes it.
  24
  25 Note in described use-case the fact that kaslr-seed is not wiped and user
  26 readable through /sys/firmware/fdt or
  27 /sys/firmware/devicetree/base/chosen/kaslr-seed is not a security problem
  28 as kaslr is disabled anyway.
  29
  30 Signed-off-by: Alexander Kamensky <alexander.kamensky42@gmail.com>
  31 Upstream-Status: Submitted [http://lists.infradead.org/pipermail/kexec/2020-November/021740.html]
  32 ---
  33  kexec/arch/arm64/kexec-arm64.c | 14 +-------------
  34  1 file changed, 1 insertion(+), 13 deletions(-)
  35
  36 Index: kexec-tools-2.0.20/kexec/arch/arm64/kexec-arm64.c
  37 ===================================================================
  38 --- kexec-tools-2.0.20.orig/kexec/arch/arm64/kexec-arm64.c
  39 +++ kexec-tools-2.0.20/kexec/arch/arm64/kexec-arm64.c
  40 @@ -428,7 +428,7 @@ static int setup_2nd_dtb(struct dtb *dtb
  41         int len, range_len;
  42         int nodeoffset;
  43         int new_size;
  44 -       int result, kaslr_seed;
  45 +       int result;
  46
  47         result = fdt_check_header(dtb->buf);
  48
  49 @@ -499,18 +499,6 @@ static int setup_2nd_dtb(struct dtb *dtb
  50                         return result;
  51                 }
  52         } else {
  53 -               kaslr_seed = fdt64_to_cpu(*prop);
  54 -
  55 -               /* kaslr_seed must be wiped clean by primary
  56 -                * kernel during boot
  57 -                */
  58 -               if (kaslr_seed != 0) {
  59 -                       dbgprintf("%s: kaslr-seed is not wiped to 0.\n",
  60 -                                       __func__);
  61 -                       result = -EINVAL;
  62 -                       goto on_error;
  63 -               }
  64 -
  65                 /*
  66                  * Invoke the getrandom system call with
  67                  * GRND_NONBLOCK, to make sure we