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author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-02-28 19:07:01 -0600 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2020-02-29 21:52:20 -0800 |
commit | 5a8b7c4b7f95c8936cd3dcba01169cd5840e291f (patch) | |
tree | 52ada8cd35a8b1a41183d43d2972f86166049774 | |
parent | 08ca27d027c238ed3f9b9968d349cebde44d99a6 (diff) | |
download | linux-5a8b7c4b7f95c8936cd3dcba01169cd5840e291f.tar.bz2 |
arcnet: 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/uapi/linux/if_arcnet.h | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/include/uapi/linux/if_arcnet.h b/include/uapi/linux/if_arcnet.h index 683878036d76..b122cfac7128 100644 --- a/include/uapi/linux/if_arcnet.h +++ b/include/uapi/linux/if_arcnet.h @@ -60,7 +60,7 @@ struct arc_rfc1201 { __u8 proto; /* protocol ID field - varies */ __u8 split_flag; /* for use with split packets */ __be16 sequence; /* sequence number */ - __u8 payload[0]; /* space remaining in packet (504 bytes)*/ + __u8 payload[]; /* space remaining in packet (504 bytes)*/ }; #define RFC1201_HDR_SIZE 4 @@ -69,7 +69,7 @@ struct arc_rfc1201 { */ struct arc_rfc1051 { __u8 proto; /* ARC_P_RFC1051_ARP/RFC1051_IP */ - __u8 payload[0]; /* 507 bytes */ + __u8 payload[]; /* 507 bytes */ }; #define RFC1051_HDR_SIZE 1 @@ -80,7 +80,7 @@ struct arc_rfc1051 { struct arc_eth_encap { __u8 proto; /* Always ARC_P_ETHER */ struct ethhdr eth; /* standard ethernet header (yuck!) */ - __u8 payload[0]; /* 493 bytes */ + __u8 payload[]; /* 493 bytes */ }; #define ETH_ENCAP_HDR_SIZE 14 |