On Thu, Apr 08, 2021 at 10:06:44PM +0200, Alexander Egorenkov wrote:
> If the passed zImage happens to have a DTB appended, then the magic 4 bytes
> of the DTB are copied together with the kernel image. This leads to
> failed kexec boots because the decompressor finds the aforementioned
> DTB magic and falsely tries to replace the DTB passed in the register r2
> with the non-existent appended one.
>
> Signed-off-by: Alexander Egorenkov <egorenar-dev@xxxxxxxxxx>
Hi,
I also see that, on line 558 len is further expanded as follows:
/*
* The zImage length does not include its stack (4k) or its
* malloc space (64k). Include this.
*/
len += 0x11000;
Is it intentional that this patch also excludes this extra length
from the DTB? Or am I missing something?
> ---
> kexec/arch/arm/kexec-zImage-arm.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/kexec/arch/arm/kexec-zImage-arm.c b/kexec/arch/arm/kexec-zImage-arm.c
> index 925a9be..8ec289d 100644
> --- a/kexec/arch/arm/kexec-zImage-arm.c
> +++ b/kexec/arch/arm/kexec-zImage-arm.c
> @@ -382,6 +382,7 @@ int zImage_arm_load(int argc, char **argv, const char *buf, off_t len,
> unsigned int atag_offset = 0x1000; /* 4k offset from memory start */
> unsigned int extra_size = 0x8000; /* TEXT_OFFSET */
> const struct zimage_tag *tag;
> + size_t kernel_buf_size;
> size_t kernel_mem_size;
> const char *command_line;
> char *modified_cmdline = NULL;
> @@ -537,6 +538,8 @@ int zImage_arm_load(int argc, char **argv, const char *buf, off_t len,
> }
> }
>
> + kernel_buf_size = len;
> +
> /*
> * Always extend the zImage by four bytes to ensure that an appended
> * DTB image always sees an initialised value after _edata.
> @@ -759,7 +762,7 @@ int zImage_arm_load(int argc, char **argv, const char *buf, off_t len,
> add_segment(info, dtb_buf, dtb_length, dtb_offset, dtb_length);
> }
>
> - add_segment(info, buf, len, kernel_base, kernel_mem_size);
> + add_segment(info, buf, kernel_buf_size, kernel_base, kernel_mem_size);
>
> info->entry = (void*)kernel_base;
>
> --
> 2.31.1
>
>
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