diff options
| author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-02-28 14:26:15 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2020-02-28 21:08:37 +0100 |
| commit | 680a93166e80e43e3ff85be06005c5cfa492d852 (patch) | |
| tree | 853ebe2b13270e4e82a448b4d56c98e86f05704b | |
| parent | xdp: Replace zero-length array with flexible-array member (diff) | |
| download | linux-680a93166e80e43e3ff85be06005c5cfa492d852.tar.xz linux-680a93166e80e43e3ff85be06005c5cfa492d852.zip | |
net: mpls: 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 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | include/net/mpls_iptunnel.h | 2 | ||||
| -rw-r--r-- | net/mpls/internal.h | 4 |
2 files changed, 3 insertions, 3 deletions
diff --git a/include/net/mpls_iptunnel.h b/include/net/mpls_iptunnel.h index 6b4759eae158..9deb3a3735da 100644 --- a/include/net/mpls_iptunnel.h +++ b/include/net/mpls_iptunnel.h @@ -11,7 +11,7 @@ struct mpls_iptunnel_encap { u8 ttl_propagate; u8 default_ttl; u8 reserved1; - u32 label[0]; + u32 label[]; }; static inline struct mpls_iptunnel_encap *mpls_lwtunnel_encap(struct lwtunnel_state *lwtstate) diff --git a/net/mpls/internal.h b/net/mpls/internal.h index 768a302879b4..0e9aa94adc07 100644 --- a/net/mpls/internal.h +++ b/net/mpls/internal.h @@ -98,7 +98,7 @@ struct mpls_nh { /* next hop label forwarding entry */ u8 nh_via_table; u8 nh_reserved1; - u32 nh_label[0]; + u32 nh_label[]; }; /* offset of via from beginning of mpls_nh */ @@ -154,7 +154,7 @@ struct mpls_route { /* next hop label forwarding entry */ u8 rt_nh_size; u8 rt_via_offset; u8 rt_reserved1; - struct mpls_nh rt_nh[0]; + struct mpls_nh rt_nh[]; }; #define for_nexthops(rt) { \ |