Alec Brown 385d906007 elf: Validate elf section header table index for section name string table
In multiboot_elfxx.c, e_shstrndx is used to obtain the section header table
index of the section name string table, but it wasn't being checked if the value
was there.

According to the elf(5) manual page,
"If the index of section name string table section is larger than or equal to
SHN_LORESERVE (0xff00), this member holds SHN_XINDEX (0xffff) and the real
index of the section name string table section is held in the sh_link member of
the initial entry in section header table. Otherwise, the sh_link member of the
initial entry in section header table contains the value zero."

Since this check wasn't being made, grub_elfXX_get_shstrndx() is being added to
elfXX.c to make this check and use e_shstrndx if it doesn't have SHN_XINDEX as a
value, else use sh_link. We also need to make sure e_shstrndx isn't greater than
or equal to SHN_LORESERVE and sh_link isn't less than SHN_LORESERVE.

Note that even though elf.c and elfXX.c are located in grub-core/kern, they are
compiled as modules and don't need the EXPORT_FUNC() macro to define the functions
in elf.h.

Signed-off-by: Alec Brown <alec.r.brown@oracle.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2022-08-19 22:26:53 +02:00
2012-02-23 17:21:38 +01:00
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This is GRUB 2, the second version of the GRand Unified Bootloader.
GRUB 2 is rewritten from scratch to make GNU GRUB cleaner, safer, more
robust, more powerful, and more portable.

See the file NEWS for a description of recent changes to GRUB 2.

See the file INSTALL for instructions on how to build and install the
GRUB 2 data and program files.

See the file MAINTAINERS for information about the GRUB maintainers, etc.

If you found a security vulnerability in the GRUB please check the SECURITY
file to get more information how to properly report this kind of bugs to
the maintainers.

Please visit the official web page of GRUB 2, for more information.
The URL is <http://www.gnu.org/software/grub/grub.html>.

More extensive documentation is available in the Info manual,
accessible using 'info grub' after building and installing GRUB 2.

There are a number of important user-visible differences from the
first version of GRUB, now known as GRUB Legacy. For a summary, please
see:

  info grub Introduction 'Changes from GRUB Legacy'
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