netdev - [PATCH 1/5] chelsio/l2t: Annotate struct l2t_data with __counted

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Date: Fri, 29 Sep 2023 11:11:45 -0700
From: Kees Cook <keescook@...omium.org>
To: Raju Rangoju <rajur@...lsio.com>
Cc: Kees Cook <keescook@...omium.org>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	netdev@...r.kernel.org,
	"Gustavo A. R. Silva" <gustavoars@...nel.org>,
	Nathan Chancellor <nathan@...nel.org>,
	Nick Desaulniers <ndesaulniers@...gle.com>,
	Tom Rix <trix@...hat.com>,
	linux-kernel@...r.kernel.org,
	linux-hardening@...r.kernel.org,
	llvm@...ts.linux.dev
Subject: [PATCH 1/5] chelsio/l2t: Annotate struct l2t_data with __counted_by

Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
(for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct l2t_data.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: Raju Rangoju <rajur@...lsio.com>
Cc: "David S. Miller" <davem@...emloft.net>
Cc: Eric Dumazet <edumazet@...gle.com>
Cc: Jakub Kicinski <kuba@...nel.org>
Cc: Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org
Signed-off-by: Kees Cook <keescook@...omium.org>
---
 drivers/net/ethernet/chelsio/cxgb3/l2t.h | 2 +-
 drivers/net/ethernet/chelsio/cxgb4/l2t.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/chelsio/cxgb3/l2t.h b/drivers/net/ethernet/chelsio/cxgb3/l2t.h
index ea75f275023f..646ca0bc25bd 100644
--- a/drivers/net/ethernet/chelsio/cxgb3/l2t.h
+++ b/drivers/net/ethernet/chelsio/cxgb3/l2t.h
@@ -76,7 +76,7 @@ struct l2t_data {
 	atomic_t nfree;		/* number of free entries */
 	rwlock_t lock;
 	struct rcu_head rcu_head;	/* to handle rcu cleanup */
-	struct l2t_entry l2tab[];
+	struct l2t_entry l2tab[] __counted_by(nentries);
 };
 
 typedef void (*arp_failure_handler_func)(struct t3cdev * dev,
diff --git a/drivers/net/ethernet/chelsio/cxgb4/l2t.c b/drivers/net/ethernet/chelsio/cxgb4/l2t.c
index a10a6862a9a4..1e5f5b1a22a6 100644
--- a/drivers/net/ethernet/chelsio/cxgb4/l2t.c
+++ b/drivers/net/ethernet/chelsio/cxgb4/l2t.c
@@ -59,7 +59,7 @@ struct l2t_data {
 	rwlock_t lock;
 	atomic_t nfree;             /* number of free entries */
 	struct l2t_entry *rover;    /* starting point for next allocation */
-	struct l2t_entry l2tab[];  /* MUST BE LAST */
+	struct l2t_entry l2tab[] __counted_by(l2t_size);  /* MUST BE LAST */
 };
 
 static inline unsigned int vlan_prio(const struct l2t_entry *e)
-- 
2.34.1