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Date:   Fri, 15 Sep 2023 13:01:23 -0600
From:   "Gustavo A. R. Silva" <gustavoars@kernel.org>
To:     Ido Schimmel <idosch@nvidia.com>, Petr Machata <petrm@nvidia.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        "Gustavo A. R. Silva" <gustavoars@kernel.org>,
        linux-hardening@vger.kernel.org
Subject: [PATCH][next] mlxsw: Use size_mul() in call to struct_size()
Message-ID: <ZQSqA80YyLQsnd1L@work>
MIME-Version: 1.0
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Precedence: bulk

If, for any reason, the open-coded arithmetic causes a wraparound, the
protection that `struct_size()` adds against potential integer overflows
is defeated. Fix this by hardening call to `struct_size()` with `size_mul()`.

Fixes: 2285ec872d9d ("mlxsw: spectrum_acl_bloom_filter: use struct_size() in kzalloc()")
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_bloom_filter.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_bloom_filter.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_bloom_filter.c
index e2aced7ab454..95f63fcf4ba1 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_bloom_filter.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_bloom_filter.c
@@ -496,7 +496,7 @@ mlxsw_sp_acl_bf_init(struct mlxsw_sp *mlxsw_sp, unsigned int num_erp_banks)
 	 * is 2^ACL_MAX_BF_LOG
 	 */
 	bf_bank_size = 1 << MLXSW_CORE_RES_GET(mlxsw_sp->core, ACL_MAX_BF_LOG);
-	bf = kzalloc(struct_size(bf, refcnt, bf_bank_size * num_erp_banks),
+	bf = kzalloc(struct_size(bf, refcnt, size_mul(bf_bank_size, num_erp_banks)),
 		     GFP_KERNEL);
 	if (!bf)
 		return ERR_PTR(-ENOMEM);
-- 
2.34.1