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ndisc: Replace zero-length array with flexible-array member
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>
This commit is contained in:
parent
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1 changed files with 3 additions and 3 deletions
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@ -80,12 +80,12 @@ extern struct neigh_table nd_tbl;
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struct nd_msg {
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struct icmp6hdr icmph;
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struct in6_addr target;
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__u8 opt[0];
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__u8 opt[];
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};
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struct rs_msg {
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struct icmp6hdr icmph;
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__u8 opt[0];
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__u8 opt[];
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};
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struct ra_msg {
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@ -98,7 +98,7 @@ struct rd_msg {
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struct icmp6hdr icmph;
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struct in6_addr target;
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struct in6_addr dest;
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__u8 opt[0];
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__u8 opt[];
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};
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struct nd_opt_hdr {
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