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680a93166e
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.
Also, notice that, dynamic memory allocations won't be affected by
this change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]
This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
22 lines
429 B
C
22 lines
429 B
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (c) 2015 Cumulus Networks, Inc.
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*/
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#ifndef _NET_MPLS_IPTUNNEL_H
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#define _NET_MPLS_IPTUNNEL_H 1
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struct mpls_iptunnel_encap {
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u8 labels;
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u8 ttl_propagate;
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u8 default_ttl;
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u8 reserved1;
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u32 label[];
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};
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static inline struct mpls_iptunnel_encap *mpls_lwtunnel_encap(struct lwtunnel_state *lwtstate)
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{
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return (struct mpls_iptunnel_encap *)lwtstate->data;
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}
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#endif
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