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Filename Latest commit message Latest commit date
Kees Cook 9ddeea35c4 mm/slub: fix redzoning for small allocations
commit 74c1d3e081533825f2611e46edea1fcdc0701985 upstream.

The redzone area for SLUB exists between s->object_size and s->inuse
(which is at least the word-aligned object_size).  If a cache were
created with an object_size smaller than sizeof(void *), the in-object
stored freelist pointer would overwrite the redzone (e.g.  with boot
param "slub_debug=ZF"):

  BUG test (Tainted: G    B            ): Right Redzone overwritten
  -----------------------------------------------------------------------------

  INFO: 0xffff957ead1c05de-0xffff957ead1c05df @offset=1502. First byte 0x1a instead of 0xbb
  INFO: Slab 0xffffef3950b47000 objects=170 used=170 fp=0x0000000000000000 flags=0x8000000000000200
  INFO: Object 0xffff957ead1c05d8 @offset=1496 fp=0xffff957ead1c0620

  Redzone  (____ptrval____): bb bb bb bb bb bb bb bb    ........
  Object   (____ptrval____): f6 f4 a5 40 1d e8          ...@..
  Redzone  (____ptrval____): 1a aa                      ..
  Padding  (____ptrval____): 00 00 00 00 00 00 00 00    ........

Store the freelist pointer out of line when object_size is smaller than
sizeof(void *) and redzoning is enabled.

Additionally remove the "smaller than sizeof(void *)" check under
CONFIG_DEBUG_VM in kmem_cache_sanity_check() as it is now redundant:
SLAB and SLOB both handle small sizes.

(Note that no caches within this size range are known to exist in the
kernel currently.)

Link: https://lkml.kernel.org/r/20210608183955.280836-3-keescook@chromium.org
Fixes: 81819f0fc8 ("SLUB core")
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: "Lin, Zhenpeng" <zplin@psu.edu>
Cc: Marco Elver <elver@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-06-23 14:41:30 +02:00
arch x86/fpu: Reset state for all signal restore failures 2021-06-23 14:41:29 +02:00
block
certs
crypto
Documentation mm/slub: clarify verification reporting 2021-06-23 14:41:30 +02:00
drivers net: ll_temac: Fix TX BD buffer overwrite 2021-06-23 14:41:30 +02:00
fs afs: Fix an IS_ERR() vs NULL check 2021-06-23 14:41:23 +02:00
include regulator: bd70528: Fix off-by-one for buck123 .n_voltages setting 2021-06-23 14:41:27 +02:00
init
ipc
kernel tracing: Do no increment trace_clock_global() by one 2021-06-23 14:41:28 +02:00
lib
LICENSES
mm mm/slub: fix redzoning for small allocations 2021-06-23 14:41:30 +02:00
net net: bridge: fix vlan tunnel dst refcnt when egressing 2021-06-23 14:41:30 +02:00
samples
scripts
security
sound ASoC: rt5659: Fix the lost powers for the HDA header 2021-06-23 14:41:27 +02:00
tools
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README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.