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b7dfa8895f
The i386 ABI disagrees with most other ABIs regarding alignment of
data types larger than 4 bytes: on most ABIs a padding must be added
at end of the structures, while it is not required on i386.
So for most ABI struct c4iw_alloc_ucontext_resp gets implicitly padded
to be aligned on a 8 bytes multiple, while for i386, such padding is
not added.
The tool pahole can be used to find such implicit padding:
$ pahole --anon_include \
--nested_anon_include \
--recursive \
--class_name c4iw_alloc_ucontext_resp \
drivers/infiniband/hw/cxgb4/iw_cxgb4.o
Then, structure layout can be compared between i386 and x86_64:
+++ obj-i386/drivers/infiniband/hw/cxgb4/iw_cxgb4.o.pahole.txt 2014-03-28 11:43:05.547432195 +0100
--- obj-x86_64/drivers/infiniband/hw/cxgb4/iw_cxgb4.o.pahole.txt 2014-03-28 10:55:10.990133017 +0100
@@ -2,9 +2,8 @@ struct c4iw_alloc_ucontext_resp {
__u64 status_page_key; /* 0 8 */
__u32 status_page_size; /* 8 4 */
- /* size: 12, cachelines: 1, members: 2 */
- /* last cacheline: 12 bytes */
+ /* size: 16, cachelines: 1, members: 2 */
+ /* padding: 4 */
+ /* last cacheline: 16 bytes */
};
This ABI disagreement will make an x86_64 kernel try to write past the
buffer provided by an i386 binary.
When boundary check will be implemented, the x86_64 kernel will refuse
to write past the i386 userspace provided buffer and the uverbs will
fail.
If the structure is on a page boundary and the next page is not
mapped, ib_copy_to_udata() will fail and the uverb will fail.
Additionally, as reported by Dan Carpenter, without the implicit
padding being properly cleared, an information leak would take place
in most architectures.
This patch adds an explicit padding to struct c4iw_alloc_ucontext_resp,
and, like 92b0ca7cb1 ("IB/mlx5: Fix stack info leak in
mlx5_ib_alloc_ucontext()"), makes function c4iw_alloc_ucontext()
not writting this padding field to userspace. This way, x86_64 kernel
will be able to write struct c4iw_alloc_ucontext_resp as expected by
unpatched and patched i386 libcxgb4.
Link: http://marc.info/?i=cover.1399309513.git.ydroneaud@opteya.com
Link: http://marc.info/?i=1395848977.3297.15.camel@localhost.localdomain
Link: http://marc.info/?i=20140328082428.GH25192@mwanda
Cc: <stable@vger.kernel.org>
Fixes: 05eb23893c ("cxgb4/iw_cxgb4: Doorbell Drop Avoidance Bug Fixes")
Reported-by: Yann Droneaud <ydroneaud@opteya.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Yann Droneaud <ydroneaud@opteya.com>
Acked-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
81 lines
2.4 KiB
C
81 lines
2.4 KiB
C
/*
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* Copyright (c) 2009-2010 Chelsio, Inc. All rights reserved.
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*
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* This software is available to you under a choice of one of two
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* licenses. You may choose to be licensed under the terms of the GNU
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* General Public License (GPL) Version 2, available from the file
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* COPYING in the main directory of this source tree, or the
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* OpenIB.org BSD license below:
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*
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* Redistribution and use in source and binary forms, with or
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* without modification, are permitted provided that the following
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* conditions are met:
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*
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* - Redistributions of source code must retain the above
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* copyright notice, this list of conditions and the following
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* disclaimer.
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*
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* - Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following
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* disclaimer in the documentation and/or other materials
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* provided with the distribution.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#ifndef __C4IW_USER_H__
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#define __C4IW_USER_H__
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#define C4IW_UVERBS_ABI_VERSION 2
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/*
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* Make sure that all structs defined in this file remain laid out so
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* that they pack the same way on 32-bit and 64-bit architectures (to
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* avoid incompatibility between 32-bit userspace and 64-bit kernels).
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* In particular do not use pointer types -- pass pointers in __u64
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* instead.
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*/
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struct c4iw_create_cq_resp {
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__u64 key;
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__u64 gts_key;
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__u64 memsize;
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__u32 cqid;
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__u32 size;
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__u32 qid_mask;
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__u32 reserved; /* explicit padding (optional for i386) */
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};
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enum {
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C4IW_QPF_ONCHIP = (1<<0)
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};
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struct c4iw_create_qp_resp {
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__u64 ma_sync_key;
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__u64 sq_key;
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__u64 rq_key;
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__u64 sq_db_gts_key;
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__u64 rq_db_gts_key;
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__u64 sq_memsize;
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__u64 rq_memsize;
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__u32 sqid;
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__u32 rqid;
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__u32 sq_size;
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__u32 rq_size;
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__u32 qid_mask;
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__u32 flags;
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};
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struct c4iw_alloc_ucontext_resp {
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__u64 status_page_key;
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__u32 status_page_size;
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__u32 reserved; /* explicit padding (optional for i386) */
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};
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#endif
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