* [dpdk-stable] Fwd: [PATCH v3] lib/rte_rib6: fix stack buffer overflow
[not found] ` <20210621132834.21673-1-ohilyard@iol.unh.edu>
@ 2021-06-21 13:30 ` Owen Hilyard
2021-06-23 15:17 ` [dpdk-stable] [PATCH v4] rib: fix max depth IPv6 lookup ohilyard
1 sibling, 0 replies; 3+ messages in thread
From: Owen Hilyard @ 2021-06-21 13:30 UTC (permalink / raw)
To: dpdk stable
Sorry about the forward, I forgot to CC stable when I sent it out.
---------- Forwarded message ---------
From: <ohilyard@iol.unh.edu>
Date: Mon, Jun 21, 2021 at 9:28 AM
Subject: [PATCH v3] lib/rte_rib6: fix stack buffer overflow
To: <vladimir.medvedkin@intel.com>
Cc: <dev@dpdk.org>, <stephen@networkplumber.org>, <david.marchand@redhat.com>,
Owen Hilyard <ohilyard@iol.unh.edu>
From: Owen Hilyard <ohilyard@iol.unh.edu>
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 <ohilyard@iol.unh.edu>
---
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
^ permalink raw reply [flat|nested] 3+ messages in thread* [dpdk-stable] [PATCH v4] rib: fix max depth IPv6 lookup
[not found] ` <20210621132834.21673-1-ohilyard@iol.unh.edu>
2021-06-21 13:30 ` [dpdk-stable] Fwd: [PATCH v3] lib/rte_rib6: fix stack buffer overflow Owen Hilyard
@ 2021-06-23 15:17 ` ohilyard
2021-06-24 13:23 ` David Marchand
1 sibling, 1 reply; 3+ messages in thread
From: ohilyard @ 2021-06-23 15:17 UTC (permalink / raw)
To: vladimir.medvedkin; +Cc: dev, stable, stephen, david.marchand, Owen Hilyard
From: Owen Hilyard <ohilyard@iol.unh.edu>
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 <ohilyard@iol.unh.edu>
---
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
^ permalink raw reply [flat|nested] 3+ messages in thread