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authorGustavo A. R. Silva <gustavo@embeddedor.com>2020-02-27 14:58:44 -0600
committerDavid S. Miller <davem@davemloft.net>2020-02-29 21:27:02 -0800
commitb90feaff2a2cbf339069adec4bfd6091cfb44b50 (patch)
tree93bd8729ec50413d5a530bb7567abf4302de0fbd
parentMerge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next (diff)
downloadlinux-dev-b90feaff2a2cbf339069adec4bfd6091cfb44b50.tar.xz
linux-dev-b90feaff2a2cbf339069adec4bfd6091cfb44b50.zip
net: sched: 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/pkt_sched.h2
-rw-r--r--net/sched/em_ipt.c2
-rw-r--r--net/sched/em_nbyte.c2
-rw-r--r--net/sched/sch_atm.c2
-rw-r--r--net/sched/sch_netem.c2
5 files changed, 5 insertions, 5 deletions
diff --git a/include/net/pkt_sched.h b/include/net/pkt_sched.h
index 6a70845bd9ab..20d2c6419612 100644
--- a/include/net/pkt_sched.h
+++ b/include/net/pkt_sched.h
@@ -181,7 +181,7 @@ struct tc_taprio_qopt_offload {
u64 cycle_time_extension;
size_t num_entries;
- struct tc_taprio_sched_entry entries[0];
+ struct tc_taprio_sched_entry entries[];
};
/* Reference counting */
diff --git a/net/sched/em_ipt.c b/net/sched/em_ipt.c
index 9fff6480acc6..eecfe072c508 100644
--- a/net/sched/em_ipt.c
+++ b/net/sched/em_ipt.c
@@ -22,7 +22,7 @@ struct em_ipt_match {
const struct xt_match *match;
u32 hook;
u8 nfproto;
- u8 match_data[0] __aligned(8);
+ u8 match_data[] __aligned(8);
};
struct em_ipt_xt_match {
diff --git a/net/sched/em_nbyte.c b/net/sched/em_nbyte.c
index 88c7ce42df7e..2c1192a2ee5e 100644
--- a/net/sched/em_nbyte.c
+++ b/net/sched/em_nbyte.c
@@ -16,7 +16,7 @@
struct nbyte_data {
struct tcf_em_nbyte hdr;
- char pattern[0];
+ char pattern[];
};
static int em_nbyte_change(struct net *net, void *data, int data_len,
diff --git a/net/sched/sch_atm.c b/net/sched/sch_atm.c
index f4f9b8cdbffb..ee12ca9f55b4 100644
--- a/net/sched/sch_atm.c
+++ b/net/sched/sch_atm.c
@@ -58,7 +58,7 @@ struct atm_flow_data {
struct atm_flow_data *excess; /* flow for excess traffic;
NULL to set CLP instead */
int hdr_len;
- unsigned char hdr[0]; /* header data; MUST BE LAST */
+ unsigned char hdr[]; /* header data; MUST BE LAST */
};
struct atm_qdisc_data {
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index 42e557d48e4e..84f82771cdf5 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -66,7 +66,7 @@
struct disttable {
u32 size;
- s16 table[0];
+ s16 table[];
};
struct netem_sched_data {