[bug #38773] Loading ELF image via multiboot2 fails

[Leon Drugi]

URL:
  <http://savannah.gnu.org/bugs/?38773>

                 Summary: Loading ELF image via multiboot2 fails
                 Project: GNU GRUB
            Submitted by: eyak
            Submitted on: Fri 19 Apr 2013 04:19:35 AM GMT
                Category: Booting
                Severity: Major
                Priority: 5 - Normal
              Item Group: Software Error
                  Status: None
                 Privacy: Public
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 
                 Release: other
         Reproducibility: Every Time
         Planned Release: None

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Details:

Hello,

I use multiboot2 feature to load ELF image and found a bug in GRUB2 version
1.99. In the ELF multiboot2 header I use both MULTIBOOT_HEADER_TAG_ADDRESS and
MULTIBOOT_HEADER_TAG_ENTRY_ADDRESS options. The problem is with cleaning BSS
section. The original code in grub_multiboot_load() function in
multiboot_mbi2.c makes grub_uint32_t* cast instead of grub_uint8_t*(as for
multiboot booting). In the final result the base address of cleaned memory is
source + 4*load_size, because of this casting.

So the code:
-------------
 if (addr_tag->bss_end_addr)
        grub_memset ((grub_uint32_t *) source + load_size, 0,
                     addr_tag->bss_end_addr - addr_tag->load_addr - load_size);
-------------
should be replaced with:
-------------
 if (addr_tag->bss_end_addr)
        grub_memset ((grub_uint8_t *) source + load_size, 0,
                     addr_tag->bss_end_addr - addr_tag->load_addr - load_size);
-------------

In the final result the ELF image loading may hang the board depends on BSS
section size as in my case.

Regards
Leon




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