net: sched: Use struct_size() helper in kvmalloc()

Make use of the struct_size() helper instead of an open-coded version,
in order to avoid any potential type mistakes or integer overflows
that, in the worst scenario, could lead to heap overflows.

Link: https://github.com/KSPP/linux/issues/160
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20210929201718.GA342296@embeddedor
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index 0c345e4..ecbb10d 100644 (file)
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -785,7 +785,7 @@ static int get_dist_table(struct Qdisc *sch, struct disttable **tbl,
        if (!n || n > NETEM_DIST_MAX)
                return -EINVAL;
 
-       d = kvmalloc(sizeof(struct disttable) + n * sizeof(s16), GFP_KERNEL);
+       d = kvmalloc(struct_size(d, table, n), GFP_KERNEL);
        if (!d)
                return -ENOMEM;