From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wj0-f199.google.com (mail-wj0-f199.google.com [209.85.210.199]) by kanga.kvack.org (Postfix) with ESMTP id 7C4896B02FE for ; Tue, 20 Dec 2016 08:07:10 -0500 (EST) Received: by mail-wj0-f199.google.com with SMTP id he10so53284366wjc.6 for ; Tue, 20 Dec 2016 05:07:10 -0800 (PST) Received: from mail-wj0-f193.google.com (mail-wj0-f193.google.com. [209.85.210.193]) by mx.google.com with ESMTPS id 63si18925597wmo.42.2016.12.20.05.07.09 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 20 Dec 2016 05:07:09 -0800 (PST) Received: by mail-wj0-f193.google.com with SMTP id he10so27636665wjc.2 for ; Tue, 20 Dec 2016 05:07:09 -0800 (PST) From: Michal Hocko Subject: [PATCH 1/2] mm, slab: make sure that KMALLOC_MAX_SIZE will fit into MAX_ORDER Date: Tue, 20 Dec 2016 14:06:58 +0100 Message-Id: <20161220130659.16461-2-mhocko@kernel.org> In-Reply-To: <20161220130659.16461-1-mhocko@kernel.org> References: <20161220130659.16461-1-mhocko@kernel.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Cristopher Lameter , Alexei Starovoitov , Andrey Konovalov , netdev@vger.kernel.org, linux-mm@kvack.org, LKML , Michal Hocko From: Michal Hocko 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 [] dump_stack+0x292/0x398 lib/dump_stack.c:51 [] panic+0x1cb/0x3a9 kernel/panic.c:179 [] __warn+0x1c4/0x1e0 kernel/panic.c:542 [] warn_slowpath_null+0x2c/0x40 kernel/panic.c:585 [< inline >] __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 [< inline >] 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 [< inline >] kmalloc_large include/linux/slab.h:422 [] __kmalloc+0x210/0x2d0 mm/slub.c:3723 [< inline >] kmalloc include/linux/slab.h:495 [] ep_write_iter+0x167/0xb50 drivers/usb/gadget/legacy/inode.c:664 [< inline >] 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 [< inline >] 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. Reported-by: Andrey Konovalov Signed-off-by: Michal Hocko Acked-by: Christoph Lameter --- include/linux/slab.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/include/linux/slab.h b/include/linux/slab.h index 084b12bad198..4c5363566815 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -226,7 +226,7 @@ static inline const char *__check_heap_object(const void *ptr, * (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_object(const void *ptr, * 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 -- 2.10.2 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org