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The out->ncomb is a bit-field of 8 bits. So, the max possible value is 255. However, code in grub_unicode_aglomerate_comb() doesn't check for an overflow when incrementing out->ncomb. If out->ncomb is already 255, after incrementing it will get 0 instead of 256, and cause illegal memory access in subsequent processing. This patch introduces GRUB_UNICODE_NCOMB_MAX to represent the max acceptable value of ncomb. The code now checks for this limit and ignores additional combining characters when limit is reached. Reported-by: Daniel Axtens <dja@axtens.net> Signed-off-by: Zhang Boyang <zhangboyang.id@gmail.com> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
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'