From 33e41066d60ef3e10f1dca12d266448a369049ed Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Fri, 28 Feb 2020 07:43:24 -0600 Subject: [PATCH] UPSTREAM: [shouldgobefore] BACKPORT: net: core: 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") Change-Id: I2d08932be34afea2136c60991c09479553110872 Signed-off-by: Gustavo A. R. Silva Signed-off-by: David S. Miller --- net/core/bpf_sk_storage.c | 2 +- net/core/devlink.c | 2 +- net/core/drop_monitor.c | 2 +- 3 files changed, 3 insertions(+), 3 deletions(-) diff --git a/net/core/bpf_sk_storage.c b/net/core/bpf_sk_storage.c index bbc6c6ea0d75..cd8b7017913b 100644 --- a/net/core/bpf_sk_storage.c +++ b/net/core/bpf_sk_storage.c @@ -61,7 +61,7 @@ struct bpf_local_storage_data { * the number of cachelines access during the cache hit case. */ struct bpf_local_storage_map __rcu *smap; - u8 data[0] __aligned(8); + u8 data[] __aligned(8); }; /* Linked to bpf_local_storage and bpf_local_storage_map */ diff --git a/net/core/devlink.c b/net/core/devlink.c index 5bd6330ab427..77770ef6c6ee 100644 --- a/net/core/devlink.c +++ b/net/core/devlink.c @@ -4127,7 +4127,7 @@ struct devlink_fmsg_item { int attrtype; u8 nla_type; u16 len; - int value[0]; + int value[]; }; struct devlink_fmsg { diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c index 1c6237a88acc..3edde3bf2f80 100644 --- a/net/core/drop_monitor.c +++ b/net/core/drop_monitor.c @@ -67,7 +67,7 @@ struct net_dm_hw_entry { struct net_dm_hw_entries { u32 num_entries; - struct net_dm_hw_entry entries[0]; + struct net_dm_hw_entry entries[]; }; struct per_cpu_dm_data {