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When parsing an extremely fragmented $MFT file, i.e., the file described using the $ATTRIBUTE_LIST attribute, current NTFS code will reuse a buffer containing bytes read from the underlying drive to store sector numbers, which are consumed later to read data from these sectors into another buffer. These sectors numbers, two 32-bit integers, are always stored at predefined offsets, 0x10 and 0x14, relative to first byte of the selected entry within the $ATTRIBUTE_LIST attribute. Usually, this won't cause any problem. However, when parsing a specially-crafted file system image, this may cause the NTFS code to write these integers beyond the buffer boundary, likely causing the GRUB memory allocator to misbehave or fail. These integers contain values which are controlled by on-disk structures of the NTFS file system. Such modification and resulting misbehavior may touch a memory range not assigned to the GRUB and owned by firmware or another EFI application/driver. This fix introduces checks to ensure that these sector numbers are never written beyond the boundary. Fixes: CVE-2023-4692 Reported-by: Maxim Suhanov <dfirblog@gmail.com> Signed-off-by: Maxim Suhanov <dfirblog@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'