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authorGustavo A. R. Silva <gustavoars@kernel.org>2020-05-07 14:02:16 -0500
committerDavid S. Miller <davem@davemloft.net>2020-05-11 13:18:54 -0700
commit0fa39d6dd0478b080a420aa764280e1a3bdb0cee (patch)
tree7cc4961678396bb93ab07544bdfeadd12060d55c /include/net/if_inet6.h
parenta6f0b26d6a5dcf27980e65f965779a929039f11d (diff)
downloadlwn-0fa39d6dd0478b080a420aa764280e1a3bdb0cee.tar.gz
lwn-0fa39d6dd0478b080a420aa764280e1a3bdb0cee.zip
ipv6: Replace zero-length array with flexible-array
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] sizeof(flexible-array-member) triggers a warning because flexible array members have incomplete type[1]. There are some instances of code in which the sizeof operator is being incorrectly/erroneously applied to zero-length arrays and the result is zero. Such instances may be hiding some bugs. So, this work (flexible-array member conversions) will also help to get completely rid of those sorts of issues. 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 <gustavoars@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net/if_inet6.h')
-rw-r--r--include/net/if_inet6.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/net/if_inet6.h b/include/net/if_inet6.h
index 212eb278bda6..8bf5906073bc 100644
--- a/include/net/if_inet6.h
+++ b/include/net/if_inet6.h
@@ -78,7 +78,7 @@ struct inet6_ifaddr {
struct ip6_sf_socklist {
unsigned int sl_max;
unsigned int sl_count;
- struct in6_addr sl_addr[0];
+ struct in6_addr sl_addr[];
};
#define IP6_SFLSIZE(count) (sizeof(struct ip6_sf_socklist) + \