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Peng Fan 59090e479a mm, slub: avoid zeroing kmalloc redzone Since commit `946fa0dbf2` ("mm/slub: extend redzone check to extra allocated kmalloc space than requested"), setting orig_size treats the wasted space (object_size - orig_size) as a redzone. However with init_on_free=1 we clear the full object->size, including the redzone. Additionally we clear the object metadata, including the stored orig_size, making it zero, which makes check_object() treat the whole object as a redzone. These issues lead to the following BUG report with "slub_debug=FUZ init_on_free=1": [ 0.000000] ============================================================================= [ 0.000000] BUG kmalloc-8 (Not tainted): kmalloc Redzone overwritten [ 0.000000] ----------------------------------------------------------------------------- [ 0.000000] [ 0.000000] 0xffff000010032858-0xffff00001003285f @offset=2136. First byte 0x0 instead of 0xcc [ 0.000000] FIX kmalloc-8: Restoring kmalloc Redzone 0xffff000010032858-0xffff00001003285f=0xcc [ 0.000000] Slab 0xfffffdffc0400c80 objects=36 used=23 fp=0xffff000010032a18 flags=0x3fffe0000000200(workingset\|node=0\|zone=0\|lastcpupid=0x1ffff) [ 0.000000] Object 0xffff000010032858 @offset=2136 fp=0xffff0000100328c8 [ 0.000000] [ 0.000000] Redzone ffff000010032850: cc cc cc cc cc cc cc cc ........ [ 0.000000] Object ffff000010032858: cc cc cc cc cc cc cc cc ........ [ 0.000000] Redzone ffff000010032860: cc cc cc cc cc cc cc cc ........ [ 0.000000] Padding ffff0000100328b4: 00 00 00 00 00 00 00 00 00 00 00 00 ............ [ 0.000000] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.11.0-rc3-next-20240814-00004-g61844c55c3f4 #144 [ 0.000000] Hardware name: NXP i.MX95 19X19 board (DT) [ 0.000000] Call trace: [ 0.000000] dump_backtrace+0x90/0xe8 [ 0.000000] show_stack+0x18/0x24 [ 0.000000] dump_stack_lvl+0x74/0x8c [ 0.000000] dump_stack+0x18/0x24 [ 0.000000] print_trailer+0x150/0x218 [ 0.000000] check_object+0xe4/0x454 [ 0.000000] free_to_partial_list+0x2f8/0x5ec To address the issue, use orig_size to clear the used area. And restore the value of orig_size after clear the remaining area. When CONFIG_SLUB_DEBUG not defined, (get_orig_size()' directly returns s->object_size. So when using memset to init the area, the size can simply be orig_size, as orig_size returns object_size when CONFIG_SLUB_DEBUG not enabled. And orig_size can never be bigger than object_size. Fixes: `946fa0dbf2` ("mm/slub: extend redzone check to extra allocated kmalloc space than requested") Cc: <stable@vger.kernel.org> Reviewed-by: Feng Tang <feng.tang@intel.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Peng Fan <peng.fan@nxp.com> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>		History 2024-09-03 07:33:27 +02:00
arch	s390 updates for 6.11-rc5	2024-08-25 12:05:23 +12:00
block	block: Read max write zeroes once for __blkdev_issue_write_zeroes()	2024-08-19 09:48:59 -06:00
certs	kbuild: use $(src) instead of $(srctree)/$(src) for source directory	2024-05-10 04:34:52 +09:00
crypto	crypto: testmgr - generate power-of-2 lengths more often	2024-07-13 11:50:28 +12:00
Documentation	workqueue: Fixes for v6.11-rc4	2024-08-24 10:35:57 +08:00
drivers	s390 updates for 6.11-rc5	2024-08-25 12:05:23 +12:00
fs	bcachefs fixes for 6.11-rc5, v2	2024-08-25 17:20:48 +12:00
include	SCSI fixes on 20240824	2024-08-25 12:00:16 +12:00
init	Rust fixes for v6.11	2024-08-16 11:24:06 -07:00
io_uring	io_uring/kbuf: sanitize peek buffer setup	2024-08-21 07:16:38 -06:00
ipc	sysctl: treewide: constify the ctl_table argument of proc_handlers	2024-07-24 20:59:29 +02:00
kernel	cgroup: Fixes for v6.11-rc4	2024-08-24 10:39:18 +08:00
lib	bcachefs fixes for 6.11-rc4	2024-08-17 09:46:10 -07:00
LICENSES	LICENSES: Add the copyleft-next-0.3.1 license	2022-11-08 15:44:01 +01:00
mm	mm, slub: avoid zeroing kmalloc redzone	2024-09-03 07:33:27 +02:00
net	NFS Client Bugfixes for Linux 6.11-rc	2024-08-24 09:03:25 +08:00
rust	Rust fixes for v6.11	2024-08-16 11:24:06 -07:00
samples	treewide: remove unnecessary <linux/version.h> inclusion	2024-08-12 18:36:44 +09:00
scripts	Kbuild fixes for v6.11 (2nd)	2024-08-23 07:43:15 +08:00
security	KEYS: trusted: dcp: fix leak of blob encryption key	2024-08-15 22:01:14 +03:00
sound	Kbuild fixes for v6.11 (2nd)	2024-08-23 07:43:15 +08:00
tools	Including fixes from bluetooth and netfilter.	2024-08-23 07:47:01 +08:00
usr	initramfs: shorten cmd_initfs in usr/Makefile	2024-07-16 01:07:52 +09:00
virt	KVM: x86: Disallow read-only memslots for SEV-ES and SEV-SNP (and TDX)	2024-08-14 12:28:24 -04:00
.clang-format	Docs: Move clang-format from process/ to dev-tools/	2024-06-26 16:36:00 -06:00
.cocciconfig	scripts: add Linux .cocciconfig for coccinelle	2016-07-22 12:13:39 +02:00
.editorconfig	.editorconfig: remove trim_trailing_whitespace option	2024-06-13 16:47:52 +02:00
.get_maintainer.ignore	Add Jeff Kirsher to .get_maintainer.ignore	2024-03-08 11:36:54 +00:00
.gitattributes	.gitattributes: set diff driver for Rust source code files	2023-05-31 17:48:25 +02:00
.gitignore	kbuild: add script and target to generate pacman package	2024-07-22 01:24:22 +09:00
.mailmap	mailmap: update entry for David Heidelberg	2024-08-07 18:33:56 -07:00
.rustfmt.toml	rust: add `.rustfmt.toml`	2022-09-28 09:02:20 +02:00
COPYING	COPYING: state that all contributions really are covered by this file	2020-02-10 13:32:20 -08:00
CREDITS	tracing: Update of MAINTAINERS and CREDITS file	2024-07-18 14:08:42 -07:00
Kbuild	Kbuild updates for v6.1	2022-10-10 12:00:45 -07:00
Kconfig	kbuild: ensure full rebuild when the compiler is updated	2020-05-12 13:28:33 +09:00
MAINTAINERS	SCSI fixes on 20240824	2024-08-25 12:00:16 +12:00
Makefile	Linux 6.11-rc5	2024-08-25 19:07:11 +12:00
README	README: Fix spelling	2024-03-18 03:36:32 -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 reStructuredText 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.