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Laura Abbott aea4df4c53 mm: slub: really fix slab walking for init_on_free Commit `1b7e816fc8` ("mm: slub: Fix slab walking for init_on_free") fixed one problem with the slab walking but missed a key detail: When walking the list, the head and tail pointers need to be updated since we end up reversing the list as a result. Without doing this, bulk free is broken. One way this is exposed is a NULL pointer with slub_debug=F: ============================================================================= BUG skbuff_head_cache (Tainted: G T): Object already free ----------------------------------------------------------------------------- INFO: Slab 0x000000000d2d2f8f objects=16 used=3 fp=0x0000000064309071 flags=0x3fff00000000201 BUG: kernel NULL pointer dereference, address: 0000000000000000 Oops: 0000 [#1] PREEMPT SMP PTI RIP: 0010:print_trailer+0x70/0x1d5 Call Trace: <IRQ> free_debug_processing.cold.37+0xc9/0x149 __slab_free+0x22a/0x3d0 kmem_cache_free_bulk+0x415/0x420 __kfree_skb_flush+0x30/0x40 net_rx_action+0x2dd/0x480 __do_softirq+0xf0/0x246 irq_exit+0x93/0xb0 do_IRQ+0xa0/0x110 common_interrupt+0xf/0xf </IRQ> Given we're now almost identical to the existing debugging code which correctly walks the list, combine with that. Link: https://lkml.kernel.org/r/20191104170303.GA50361@gandi.net Link: http://lkml.kernel.org/r/20191106222208.26815-1-labbott@redhat.com Fixes: `1b7e816fc8` ("mm: slub: Fix slab walking for init_on_free") Signed-off-by: Laura Abbott <labbott@redhat.com> Reported-by: Thibaut Sautereau <thibaut.sautereau@clip-os.org> Acked-by: David Rientjes <rientjes@google.com> Tested-by: Alexander Potapenko <glider@google.com> Acked-by: Alexander Potapenko <glider@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: <clipos@ssi.gouv.fr> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2019-11-15 18:34:00 -08:00
arch	A fix & simplification for SGI IP27 exception handlers, and a small	2019-11-15 09:10:13 -08:00
block	blkcg: make blkcg_print_stat() print stats only for online blkgs	2019-11-06 17:08:38 -07:00
certs	PKCS#7: Refactor verify_pkcs7_signature()	2019-08-05 18:40:18 -04:00
crypto	Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security	2019-09-28 08:14:15 -07:00
Documentation	Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2019-11-12 10:53:24 -08:00
drivers	Two fixes for the buffered reads and O_DIRECT writes serialization	2019-11-15 10:30:24 -08:00
fs	Two fixes for the buffered reads and O_DIRECT writes serialization	2019-11-15 10:30:24 -08:00
include	Bugfixes: unwinding of KVM_CREATE_VM failure,	2019-11-12 13:19:15 -08:00
init	Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security	2019-09-28 08:14:15 -07:00
ipc	ipc/sem.c: convert to use built-in RCU list checking	2019-09-25 17:51:41 -07:00
kernel	Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2019-11-15 08:44:08 -08:00
lib	lib/xz: fix XZ_DYNALLOC to avoid useless memory reallocations	2019-11-15 18:34:00 -08:00
LICENSES	LICENSES: Rename other to deprecated	2019-05-03 06:34:32 -06:00
mm	mm: slub: really fix slab walking for init_on_free	2019-11-15 18:34:00 -08:00
net	vsock/virtio: fix sock refcnt holding during the shutdown	2019-11-08 12:17:50 -08:00
samples	samples/bpf: fix build by setting HAVE_ATTR_TEST to zero	2019-10-31 21:39:15 +01:00
scripts	arm64 fix for -rc8 / final	2019-11-15 09:14:23 -08:00
security	efi/efi_test: Lock down /dev/efi_test and require CAP_SYS_ADMIN	2019-10-31 09:40:21 +01:00
sound	ALSA: usb-audio: Fix incorrect size check for processing/extension units	2019-11-14 18:01:22 +01:00
tools	selftests: kvm: fix build with glibc >= 2.30	2019-11-13 15:48:00 +01:00
usr	kbuild: update compile-test header list for v5.4-rc2	2019-10-05 15:29:49 +09:00
virt	KVM: Add a comment describing the /dev/kvm no_compat handling	2019-11-15 10:14:04 +01:00
.clang-format	clang-format: Update with the latest for_each macro list	2019-08-31 10:00:51 +02:00
.cocciconfig
.get_maintainer.ignore	Opt out of scripts/get_maintainer.pl	2019-05-16 10:53:40 -07:00
.gitattributes
.gitignore	Modules updates for v5.4	2019-09-22 10:34:46 -07:00
.mailmap	ARM: SoC fixes	2019-11-10 13:41:59 -08:00
COPYING	COPYING: use the new text with points to the license files	2018-03-23 12:41:45 -06:00
CREDITS	MAINTAINERS: Remove Simon as Renesas SoC Co-Maintainer	2019-10-10 08:12:51 -07:00
Kbuild	kbuild: do not descend to ./Kbuild when cleaning	2019-08-21 21:03:58 +09:00
Kconfig	docs: kbuild: convert docs to ReST and rename to *.rst	2019-06-14 14:21:21 -06:00
MAINTAINERS	A fix & simplification for SGI IP27 exception handlers, and a small	2019-11-15 09:10:13 -08:00
Makefile	kbuild: tell sparse about the $ARCH	2019-11-15 00:13:23 +09:00
README	Drop all 00-INDEX files from Documentation/	2018-09-09 15:08:58 -06:00

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.