linux.git/mm/util.c, branch v5.4.301

mm: only enforce minimum stack gap size if it's sensible

2024-11-08T15:20:35+00:00

commit 69b50d4351ed924f29e3d46b159e28f70dfc707f upstream.

The generic mmap_base code tries to leave a gap between the top of the
stack and the mmap base address, but enforces a minimum gap size (MIN_GAP)
of 128MB, which is too large on some setups.  In particular, on arm tasks
without ADDR_LIMIT_32BIT, the STACK_TOP value is less than 128MB, so it's
impossible to fit such a gap in.

Only enforce this minimum if MIN_GAP < MAX_GAP, as we'd prefer to honour
MAX_GAP, which is defined proportionally, so scales better and always
leaves us with both _some_ stack space and some room for mmap.

This fixes the usercopy KUnit test suite on 32-bit arm, as it doesn't set
any personality flags so gets the default (in this case 26-bit) task size.
This test can be run with: ./tools/testing/kunit/kunit.py run --arch arm
usercopy --make_options LLVM=1

Link: https://lkml.kernel.org/r/20240803074642.1849623-2-davidgow@google.com
Fixes: dba79c3df4a2 ("arm: use generic mmap top-down layout and brk randomization")
Signed-off-by: David Gow 
Reviewed-by: Kees Cook 
Cc: Alexandre Ghiti 
Cc: Linus Walleij 
Cc: Luis Chamberlain 
Cc: Mark Rutland 
Cc: Russell King 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

random: move randomize_page() into mm where it belongs

2022-06-22T12:11:17+00:00

commit 5ad7dd882e45d7fe432c32e896e2aaa0b21746ea upstream.

randomize_page is an mm function. It is documented like one. It contains
the history of one. It has the naming convention of one. It looks
just like another very similar function in mm, randomize_stack_top().
And it has always been maintained and updated by mm people. There is no
need for it to be in random.c. In the "which shape does not look like
the other ones" test, pointing to randomize_page() is correct.

So move randomize_page() into mm/util.c, right next to the similar
randomize_stack_top() function.

This commit contains no actual code changes.

Cc: Andrew Morton 
Signed-off-by: Jason A. Donenfeld 
Signed-off-by: Greg Kroah-Hartman

mm: add kvfree_sensitive() for freeing sensitive data objects

2020-06-17T14:40:23+00:00

[ Upstream commit d4eaa2837851db2bfed572898bfc17f9a9f9151e ]

For kvmalloc'ed data object that contains sensitive information like
cryptographic keys, we need to make sure that the buffer is always cleared
before freeing it.  Using memset() alone for buffer clearing may not
provide certainty as the compiler may compile it away.  To be sure, the
special memzero_explicit() has to be used.

This patch introduces a new kvfree_sensitive() for freeing those sensitive
data objects allocated by kvmalloc().  The relevant places where
kvfree_sensitive() can be used are modified to use it.

Fixes: 4f0882491a14 ("KEYS: Avoid false positive ENOMEM error on key read")
Suggested-by: Linus Torvalds 
Signed-off-by: Waiman Long 
Signed-off-by: Andrew Morton 
Reviewed-by: Eric Biggers 
Acked-by: David Howells 
Cc: Jarkko Sakkinen 
Cc: James Morris 
Cc: "Serge E. Hallyn" 
Cc: Joe Perches 
Cc: Matthew Wilcox 
Cc: David Rientjes 
Cc: Uladzislau Rezki 
Link: http://lkml.kernel.org/r/20200407200318.11711-1-longman@redhat.com
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

arm64, mm: make randomization selected by generic topdown mmap layout

2019-09-24T22:54:11+00:00

This commits selects ARCH_HAS_ELF_RANDOMIZE when an arch uses the generic
topdown mmap layout functions so that this security feature is on by
default.

Note that this commit also removes the possibility for arm64 to have elf
randomization and no MMU: without MMU, the security added by randomization
is worth nothing.

Link: http://lkml.kernel.org/r/20190730055113.23635-6-alex@ghiti.fr
Signed-off-by: Alexandre Ghiti 
Acked-by: Catalin Marinas 
Acked-by: Kees Cook 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Luis Chamberlain 
Cc: Albert Ou 
Cc: Alexander Viro 
Cc: Christoph Hellwig 
Cc: James Hogan 
Cc: Palmer Dabbelt 
Cc: Paul Burton 
Cc: Ralf Baechle 
Cc: Russell King 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

arm64, mm: move generic mmap layout functions to mm

2019-09-24T22:54:11+00:00

arm64 handles top-down mmap layout in a way that can be easily reused by
other architectures, so make it available in mm.  It then introduces a new
config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT that can be set by other
architectures to benefit from those functions.  Note that this new config
depends on MMU being enabled, if selected without MMU support, a warning
will be thrown.

Link: http://lkml.kernel.org/r/20190730055113.23635-5-alex@ghiti.fr
Signed-off-by: Alexandre Ghiti 
Suggested-by: Christoph Hellwig 
Acked-by: Catalin Marinas 
Acked-by: Kees Cook 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Luis Chamberlain 
Cc: Albert Ou 
Cc: Alexander Viro 
Cc: James Hogan 
Cc: Palmer Dabbelt 
Cc: Paul Burton 
Cc: Ralf Baechle 
Cc: Russell King 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm, fs: move randomize_stack_top from fs to mm

2019-09-24T22:54:11+00:00

Patch series "Provide generic top-down mmap layout functions", v6.

This series introduces generic functions to make top-down mmap layout
easily accessible to architectures, in particular riscv which was the
initial goal of this series.  The generic implementation was taken from
arm64 and used successively by arm, mips and finally riscv.

Note that in addition the series fixes 2 issues:

- stack randomization was taken into account even if not necessary.

- [1] fixed an issue with mmap base which did not take into account
  randomization but did not report it to arm and mips, so by moving arm64
  into a generic library, this problem is now fixed for both
  architectures.

This work is an effort to factorize architecture functions to avoid code
duplication and oversights as in [1].

[1]: https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1429066.html

This patch (of 14):

This preparatory commit moves this function so that further introduction
of generic topdown mmap layout is contained only in mm/util.c.

Link: http://lkml.kernel.org/r/20190730055113.23635-2-alex@ghiti.fr
Signed-off-by: Alexandre Ghiti 
Acked-by: Kees Cook 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Luis Chamberlain 
Cc: Russell King 
Cc: Catalin Marinas 
Cc: Will Deacon 
Cc: Ralf Baechle 
Cc: Paul Burton 
Cc: James Hogan 
Cc: Palmer Dabbelt 
Cc: Albert Ou 
Cc: Alexander Viro 
Cc: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: move memcmp_pages() and pages_identical()

2019-09-24T22:54:11+00:00

Patch series "THP aware uprobe", v13.

This patchset makes uprobe aware of THPs.

Currently, when uprobe is attached to text on THP, the page is split by
FOLL_SPLIT.  As a result, uprobe eliminates the performance benefit of
THP.

This set makes uprobe THP-aware.  Instead of FOLL_SPLIT, we introduces
FOLL_SPLIT_PMD, which only split PMD for uprobe.

After all uprobes within the THP are removed, the PTE-mapped pages are
regrouped as huge PMD.

This set (plus a few THP patches) is also available at

   https://github.com/liu-song-6/linux/tree/uprobe-thp

This patch (of 6):

Move memcmp_pages() to mm/util.c and pages_identical() to mm.h, so that we
can use them in other files.

Link: http://lkml.kernel.org/r/20190815164525.1848545-2-songliubraving@fb.com
Signed-off-by: Song Liu 
Acked-by: Kirill A. Shutemov 
Reviewed-by: Oleg Nesterov 
Cc: Johannes Weiner 
Cc: Matthew Wilcox 
Cc: William Kucharski 
Cc: Srikar Dronamraju 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: introduce compound_nr()

2019-09-24T22:54:08+00:00

Replace 1 << compound_order(page) with compound_nr(page).  Minor
improvements in readability.

Link: http://lkml.kernel.org/r/20190721104612.19120-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) 
Reviewed-by: Andrew Morton 
Reviewed-by: Ira Weiny 
Acked-by: Kirill A. Shutemov 
Cc: Michal Hocko 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: add account_locked_vm utility function

2019-07-17T02:23:25+00:00

locked_vm accounting is done roughly the same way in five places, so
unify them in a helper.

Include the helper's caller in the debug print to distinguish between
callsites.

Error codes stay the same, so user-visible behavior does too.  The one
exception is that the -EPERM case in tce_account_locked_vm is removed
because Alexey has never seen it triggered.

[daniel.m.jordan@oracle.com: v3]
  Link: http://lkml.kernel.org/r/20190529205019.20927-1-daniel.m.jordan@oracle.com
[sfr@canb.auug.org.au: fix mm/util.c]
Link: http://lkml.kernel.org/r/20190524175045.26897-1-daniel.m.jordan@oracle.com
Signed-off-by: Daniel Jordan 
Signed-off-by: Stephen Rothwell 
Tested-by: Alexey Kardashevskiy 
Acked-by: Alex Williamson 
Cc: Alan Tull 
Cc: Alex Williamson 
Cc: Benjamin Herrenschmidt 
Cc: Christoph Lameter 
Cc: Christophe Leroy 
Cc: Davidlohr Bueso 
Cc: Jason Gunthorpe 
Cc: Mark Rutland 
Cc: Michael Ellerman 
Cc: Moritz Fischer 
Cc: Paul Mackerras 
Cc: Steve Sistare 
Cc: Wu Hao 
Cc: Ira Weiny 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: consolidate the get_user_pages* implementations

2019-07-12T18:05:45+00:00

Always build mm/gup.c so that we don't have to provide separate nommu
stubs.  Also merge the get_user_pages_fast and __get_user_pages_fast stubs
when HAVE_FAST_GUP into the main implementations, which will never call
the fast path if HAVE_FAST_GUP is not set.

This also ensures the new put_user_pages* helpers are available for nommu,
as those are currently missing, which would create a problem as soon as we
actually grew users for it.

Link: http://lkml.kernel.org/r/20190625143715.1689-13-hch@lst.de
Signed-off-by: Christoph Hellwig 
Cc: Andrey Konovalov 
Cc: Benjamin Herrenschmidt 
Cc: David Miller 
Cc: James Hogan 
Cc: Jason Gunthorpe 
Cc: Khalid Aziz 
Cc: Michael Ellerman 
Cc: Nicholas Piggin 
Cc: Paul Burton 
Cc: Paul Mackerras 
Cc: Ralf Baechle 
Cc: Rich Felker 
Cc: Yoshinori Sato 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds