lkml.org 
[lkml]   [2021]   [Jan]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: UBSAN: shift-out-of-bounds in exfat_fill_super
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.

\
 
 \ /
  Last update: 2021-01-26 03:33    [W:0.053 / U:0.072 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site