Bug#1100470: Segfault with NTFS CVE fixes

[Felix Zielcke]

Hi,

on Debian we got a bug report with a segfault in grub-mount when we
added the CVE fixes to it:

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1100470

It crashes on all 3 Windows NTFS Partitions with this:

Program received signal SIGSEGV, Segmentation fault.
Download failed: Invalid argument.  Continuing without source file
./obj/grub-pc/../../grub-core/fs/ntfs.c.
0x000055555557de34 in find_attr (at=at at entry=0x555555694ea0,
     attr=attr at entry=128 '\200') at ../../grub-core/fs/ntfs.c:390
warning: 390    ../../grub-core/fs/ntfs.c: No such file or directory

Line 390 is the same AFAICS on upstream grub.git and Debian packaging:

while (at->attr_cur < mft_end && *at->attr_cur != 0xFF)

I don't know what is special on their NTFS partitions. I can't
reproduce this with my own dual-boot system.