Re: [PATCH 4.4 00/24] 4.4.137-stable review

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Wed, Jun 13, 2018 at 10:48:50PM -0300, Rafael Tinoco wrote:
> On 13 June 2018 at 18:08, Rafael David Tinoco
> <rafaeldtinoco@kernelpath.com> wrote:
> > On Wed, Jun 13, 2018 at 6:00 PM, Greg Kroah-Hartman
> > <gregkh@linuxfoundation.org> wrote:
> >> On Wed, Jun 13, 2018 at 05:47:49PM -0300, Rafael Tinoco wrote:
> >>> Results from Linaro’s test farm.
> >>> Regressions detected.
> >>>
> >>> NOTE:
> >>>
> >>> 1) LTP vma03 test (cve-2011-2496) broken on v4.4-137-rc1 because of:
> >>>
> >>>      6ea1dc96a03a mmap: relax file size limit for regular files
> >>>      bd2f9ce5bacb mmap: introduce sane default mmap limits
> >>>
> >>>    discussion:
> >>>
> >>>      https://github.com/linux-test-project/ltp/issues/341
> >>>
> >>>    mainline commit (v4.13-rc7):
> >>>
> >>>      0cc3b0ec23ce Clarify (and fix) MAX_LFS_FILESIZE macros
> >>>
> >>>    should be backported to 4.4.138-rc2 and fixes the issue.
> >>
> >> Really?  That commit says it fixes c2a9737f45e2 ("vfs,mm: fix a dead
> >> loop in truncate_inode_pages_range()") which is not in 4.4.y at all.
> >>
> >> Did you test this out?
> >
> > Yes, the LTP contains the tests (last comment is the final test for
> > arm32, right before Jan tests i686).
> >
> > Fixing MAX_LFS_FILESIZE fixes the new limit for mmap() brought by
> > those 2 commits (file_mmap_size_max()).
> > offset tested by the LTP test is 0xfffffffe000.
> > file_mmap_size_max gives: 0xFFFFFFFF000 as max value, but only after
> > the mentioned patch.
> >
> > Original intent for this fix was other though.
> 
> To clarify this a bit further.
> 
> The LTP CVE test is breaking in the first call to mmap(), even before
> trying to remap and test the security issue. That start happening in
> this round because of those mmap() changes and the offset used in the
> LTP test. Linus changed limit checks and made them to be related to
> MAX_LFS_FILESIZE. Unfortunately, in 4.4 stable, we were missing the
> fix for MAX_LFS_FILESIZE (which before commit 0cc3b0ec23ce was less
> than the REAL 32 bit limit).
> 
> Commit 0cc3b0ec23ce was made because an user noticed the FS limit not
> being what it should be. In our case, the 4.4 stable kernel, we are
> facing this 32 bit lower limit (than the real 32 bit real limit),
> because of the LTP CVE test, so we need this fix to have the real 32
> bit limit set for that macro (mmap limits did not use that macro
> before).
> 
> I have tested in arm32 and Jan Stancek, who first responded to LTP
> issue, has tested this in i686 and both worked after that patch was
> included to v4.4-137-rc1 (my last test was even with 4.4.138-rc1).
> 
> Hope that helps a bit.

Ok, thanks, it didn't apply cleanly but I've fixed it up now.

greg k-h