This is a note to let you know that I've just added the patch titled
mm, slab: make sure that KMALLOC_MAX_SIZE will fit into MAX_ORDER
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-slab-make-sure-that-kmalloc_max_size-will-fit-into-max_order.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Wed Aug 9 11:19:16 PDT 2017
From: Michal Hocko <mhocko@xxxxxxxx>
Date: Tue, 10 Jan 2017 16:57:27 -0800
Subject: mm, slab: make sure that KMALLOC_MAX_SIZE will fit into MAX_ORDER
From: Michal Hocko <mhocko@xxxxxxxx>
[ Upstream commit bb1107f7c6052c863692a41f78c000db792334bf ]
Andrey Konovalov has reported the following warning triggered by the
syzkaller fuzzer.
WARNING: CPU: 1 PID: 9935 at mm/page_alloc.c:3511 __alloc_pages_nodemask+0x159c/0x1e20
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 9935 Comm: syz-executor0 Not tainted 4.9.0-rc7+ #34
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
__alloc_pages_slowpath mm/page_alloc.c:3511
__alloc_pages_nodemask+0x159c/0x1e20 mm/page_alloc.c:3781
alloc_pages_current+0x1c7/0x6b0 mm/mempolicy.c:2072
alloc_pages include/linux/gfp.h:469
kmalloc_order+0x1f/0x70 mm/slab_common.c:1015
kmalloc_order_trace+0x1f/0x160 mm/slab_common.c:1026
kmalloc_large include/linux/slab.h:422
__kmalloc+0x210/0x2d0 mm/slub.c:3723
kmalloc include/linux/slab.h:495
ep_write_iter+0x167/0xb50 drivers/usb/gadget/legacy/inode.c:664
new_sync_write fs/read_write.c:499
__vfs_write+0x483/0x760 fs/read_write.c:512
vfs_write+0x170/0x4e0 fs/read_write.c:560
SYSC_write fs/read_write.c:607
SyS_write+0xfb/0x230 fs/read_write.c:599
entry_SYSCALL_64_fastpath+0x1f/0xc2
The issue is caused by a lack of size check for the request size in
ep_write_iter which should be fixed. It, however, points to another
problem, that SLUB defines KMALLOC_MAX_SIZE too large because the its
KMALLOC_SHIFT_MAX is (MAX_ORDER + PAGE_SHIFT) which means that the
resulting page allocator request might be MAX_ORDER which is too large
(see __alloc_pages_slowpath).
The same applies to the SLOB allocator which allows even larger sizes.
Make sure that they are capped properly and never request more than
MAX_ORDER order.
Link: http://lkml.kernel.org/r/20161220130659.16461-2-mhocko@xxxxxxxxxx
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Reported-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Acked-by: Christoph Lameter <cl@xxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/linux/slab.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -203,7 +203,7 @@ size_t ksize(const void *);
* (PAGE_SIZE*2). Larger requests are passed to the page allocator.
*/
#define KMALLOC_SHIFT_HIGH (PAGE_SHIFT + 1)
-#define KMALLOC_SHIFT_MAX (MAX_ORDER + PAGE_SHIFT)
+#define KMALLOC_SHIFT_MAX (MAX_ORDER + PAGE_SHIFT - 1)
#ifndef KMALLOC_SHIFT_LOW
#define KMALLOC_SHIFT_LOW 3
#endif
@@ -216,7 +216,7 @@ size_t ksize(const void *);
* be allocated from the same page.
*/
#define KMALLOC_SHIFT_HIGH PAGE_SHIFT
-#define KMALLOC_SHIFT_MAX 30
+#define KMALLOC_SHIFT_MAX (MAX_ORDER + PAGE_SHIFT - 1)
#ifndef KMALLOC_SHIFT_LOW
#define KMALLOC_SHIFT_LOW 3
#endif
Patches currently in stable-queue which might be from mhocko@xxxxxxxx are
queue-4.4/mm-slab-make-sure-that-kmalloc_max_size-will-fit-into-max_order.patch