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Subject[PATCH 4.19 216/276] cxgb3/l2t: Fix undefined behaviour
[ Upstream commit 76497732932f15e7323dc805e8ea8dc11bb587cf ]

The use of zero-sized array causes undefined behaviour when it is not
the last member in a structure. As it happens to be in this case.

Also, the current code makes use of a language extension to the C90
standard, but the preferred mechanism to declare variable-length
types such as this one is a flexible array member, introduced in

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. Which is beneficial
to cultivate a high-quality code.

Fixes: e48f129c2f20 ("[SCSI] cxgb3i: convert cdev->l2opt to use rcu to prevent NULL dereference")
Signed-off-by: Gustavo A. R. Silva <>
Signed-off-by: David S. Miller <>
Signed-off-by: Sasha Levin <>
drivers/net/ethernet/chelsio/cxgb3/l2t.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/chelsio/cxgb3/l2t.h b/drivers/net/ethernet/chelsio/cxgb3/l2t.h
index c2fd323c40782..ea75f275023ff 100644
--- a/drivers/net/ethernet/chelsio/cxgb3/l2t.h
+++ b/drivers/net/ethernet/chelsio/cxgb3/l2t.h
@@ -75,8 +75,8 @@ struct l2t_data {
struct l2t_entry *rover; /* starting point for next allocation */
atomic_t nfree; /* number of free entries */
rwlock_t lock;
- struct l2t_entry l2tab[0];
struct rcu_head rcu_head; /* to handle rcu cleanup */
+ struct l2t_entry l2tab[];

typedef void (*arp_failure_handler_func)(struct t3cdev * dev,

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