RE: UBSAN: shift-out-of-bounds in exfat_fill_super

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



> On Mon, Jan 25, 2021 at 09:33:14AM -0800, syzbot wrote:
> > UBSAN: shift-out-of-bounds in fs/exfat/super.c:471:28 shift exponent
> > 4294967294 is too large for 32-bit type 'int'
> 
> This is an integer underflow:
> 
>         sbi->dentries_per_clu = 1 <<
>                 (sbi->cluster_size_bits - DENTRY_SIZE_BITS);
> 
> I think the problem is that there is no validation of sect_per_clus_bits.
> We should check it is at least DENTRY_SIZE_BITS and probably that it's less than ... 16?  64?  I don't
> know what legitimate values are in this field, but I would imagine that 255 is completely unacceptable.
exfat specification describe sect_per_clus_bits field of boot sector could be at most 32 and
at least 0. And sect_size_bits can also affect this calculation, It also needs validation.
I will fix it.
Thanks!




[Index of Archives]     [Linux Ext4 Filesystem]     [Union Filesystem]     [Filesystem Testing]     [Ceph Users]     [Ecryptfs]     [AutoFS]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux Cachefs]     [Reiser Filesystem]     [Linux RAID]     [Samba]     [Device Mapper]     [CEPH Development]

  Powered by Linux