The patch titled
Subject: mm, slab: make sure that KMALLOC_MAX_SIZE will fit into MAX_ORDER
has been added to the -mm tree. Its filename is
mm-slab-make-sure-that-kmalloc_max_size-will-fit-into-max_order.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-slab-make-sure-that-kmalloc_max_size-will-fit-into-max_order.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-slab-make-sure-that-kmalloc_max_size-will-fit-into-max_order.patch
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------------------------------------------------------
From: Michal Hocko <mhocko@xxxxxxxx>
Subject: mm, slab: make sure that KMALLOC_MAX_SIZE will fit into MAX_ORDER
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
ffff88006949f2c8 ffffffff81f96b8a ffffffff00000200 1ffff1000d293dec
ffffed000d293de4 0000000000000a06 0000000041b58ab3 ffffffff8598b510
ffffffff81f968f8 0000000041b58ab3 ffffffff85942a58 ffffffff81432860
Call Trace:
[< inline >] __dump_stack lib/dump_stack.c:15
[<ffffffff81f96b8a>] dump_stack+0x292/0x398 lib/dump_stack.c:51
[<ffffffff8168c88e>] panic+0x1cb/0x3a9 kernel/panic.c:179
[<ffffffff812b80b4>] __warn+0x1c4/0x1e0 kernel/panic.c:542
[<ffffffff812b831c>] warn_slowpath_null+0x2c/0x40 kernel/panic.c:585
[< inline >] __alloc_pages_slowpath mm/page_alloc.c:3511
[<ffffffff816c08ac>] __alloc_pages_nodemask+0x159c/0x1e20 mm/page_alloc.c:3781
[<ffffffff817cde17>] alloc_pages_current+0x1c7/0x6b0 mm/mempolicy.c:2072
[< inline >] alloc_pages include/linux/gfp.h:469
[<ffffffff8172fd8f>] kmalloc_order+0x1f/0x70 mm/slab_common.c:1015
[<ffffffff8172fdff>] kmalloc_order_trace+0x1f/0x160 mm/slab_common.c:1026
[< inline >] kmalloc_large include/linux/slab.h:422
[<ffffffff817e01f0>] __kmalloc+0x210/0x2d0 mm/slub.c:3723
[< inline >] kmalloc include/linux/slab.h:495
[<ffffffff832262a7>] ep_write_iter+0x167/0xb50 drivers/usb/gadget/legacy/inode.c:664
[< inline >] new_sync_write fs/read_write.c:499
[<ffffffff817fdcd3>] __vfs_write+0x483/0x760 fs/read_write.c:512
[<ffffffff817ff720>] vfs_write+0x170/0x4e0 fs/read_write.c:560
[< inline >] SYSC_write fs/read_write.c:607
[<ffffffff81803b2b>] SyS_write+0xfb/0x230 fs/read_write.c:599
[<ffffffff84f47ec1>] 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>
---
include/linux/slab.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff -puN include/linux/slab.h~mm-slab-make-sure-that-kmalloc_max_size-will-fit-into-max_order include/linux/slab.h
--- a/include/linux/slab.h~mm-slab-make-sure-that-kmalloc_max_size-will-fit-into-max_order
+++ a/include/linux/slab.h
@@ -226,7 +226,7 @@ static inline const char *__check_heap_o
* (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
@@ -239,7 +239,7 @@ static inline const char *__check_heap_o
* 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 -mm which might be from mhocko@xxxxxxxx are
mm-slab-make-sure-that-kmalloc_max_size-will-fit-into-max_order.patch
bpf-do-not-use-kmalloc_shift_max.patch
mm-throttle-show_mem-from-warn_alloc.patch
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