Thread (15 messages) 15 messages, 5 authors, 2023-10-04

Re: [PATCH 1/5] chelsio/l2t: Annotate struct l2t_data with __counted_by

From: Gustavo A. R. Silva <hidden>
Date: 2023-10-01 06:33:45
Also in: linux-hardening, lkml, llvm


On 9/29/23 20:11, Kees Cook wrote:
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 <redacted>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: netdev@vger.kernel.org
Signed-off-by: Kees Cook <redacted>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Thanks
--
Gustavo
quoted hunk ↗ jump to hunk
---
  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)
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