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[132.177.123.84]) by smtp-relay.gmail.com with ESMTPS id e22sm85212oop.4.2021.06.23.08.17.32 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 23 Jun 2021 08:17:32 -0700 (PDT) X-Relaying-Domain: iol.unh.edu Received: from iol.unh.edu (unknown [IPv6:2606:4100:3880:1220:47d3:d45d:6a1c:8da0]) by postal.iol.unh.edu (Postfix) with ESMTP id 5E20B6052490; Wed, 23 Jun 2021 11:17:32 -0400 (EDT) From: ohilyard@iol.unh.edu To: vladimir.medvedkin@intel.com Cc: dev@dpdk.org, stable@dpdk.org, stephen@networkplumber.org, david.marchand@redhat.com, Owen Hilyard Date: Wed, 23 Jun 2021 11:17:29 -0400 Message-Id: <20210623151730.35276-1-ohilyard@iol.unh.edu> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210621132834.21673-1-ohilyard@iol.unh.edu> References: <20210621132834.21673-1-ohilyard@iol.unh.edu> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: [dpdk-dev] [PATCH v4] rib: fix max depth IPv6 lookup X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" From: Owen Hilyard ASAN found a stack buffer overflow in lib/rib/rte_rib6.c:get_dir. The fix for the stack buffer overflow was to make sure depth was always < 128, since when depth = 128 it caused the index into the ip address to be 16, which read off the end of the array. While trying to solve the buffer overflow, I noticed that a few changes could be made to remove the for loop entirely. Fixes: f7e861e21c ("rib: support IPv6") Signed-off-by: Owen Hilyard --- lib/rib/rte_rib6.c | 29 +++++++++++++++++++++-------- 1 file changed, 21 insertions(+), 8 deletions(-) diff --git a/lib/rib/rte_rib6.c b/lib/rib/rte_rib6.c index f6c55ee45..96424e9c9 100644 --- a/lib/rib/rte_rib6.c +++ b/lib/rib/rte_rib6.c @@ -79,20 +79,33 @@ is_covered(const uint8_t ip1[RTE_RIB6_IPV6_ADDR_SIZE], static inline int get_dir(const uint8_t ip[RTE_RIB6_IPV6_ADDR_SIZE], uint8_t depth) { - int i = 0; - uint8_t p_depth, msk; - - for (p_depth = depth; p_depth >= 8; p_depth -= 8) - i++; - - msk = 1 << (7 - p_depth); - return (ip[i] & msk) != 0; + uint8_t index, msk; + + /* + * depth & 127 clamps depth to values that will not + * read off the end of ip. + * depth is the number of bits deep into ip to traverse, and + * is incremented in blocks of 8 (1 byte). This means the last + * 3 bits are irrelevant to what the index of ip should be. + */ + index = (depth & (UINT8_MAX - 1)) / CHAR_BIT; + + /* + * msk is the bitmask used to extract the bit used to decide the + * direction of the next step of the binary search. + */ + msk = 1 << (7 - (depth & 7)); + + return (ip[index] & msk) != 0; } static inline struct rte_rib6_node * get_nxt_node(struct rte_rib6_node *node, const uint8_t ip[RTE_RIB6_IPV6_ADDR_SIZE]) { + if (node->depth == RIB6_MAXDEPTH) + return NULL; + return (get_dir(ip, node->depth)) ? node->right : node->left; } -- 2.30.2