diff mbox series

[v4] rib: fix max depth IPv6 lookup

Message ID 20210623151730.35276-1-ohilyard@iol.unh.edu (mailing list archive)
State Accepted, archived
Delegated to: David Marchand
Headers
Series [v4] rib: fix max depth IPv6 lookup |

Checks

Context Check Description
ci/checkpatch success coding style OK
ci/Intel-compilation success Compilation OK
ci/intel-Testing success Testing PASS
ci/iol-testing success Testing PASS
ci/github-robot success github build: passed
ci/iol-intel-Performance success Performance Testing PASS
ci/iol-intel-Functional success Functional Testing PASS

Commit Message

Owen Hilyard June 23, 2021, 3:17 p.m. UTC 
  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(-)

Comments

David Marchand June 24, 2021, 1:23 p.m. UTC | #1 
On Wed, Jun 23, 2021 at 5:17 PM <ohilyard@iol.unh.edu> wrote:
>
> 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")
Updated sha1.
Cc: stable@dpdk.org

>
> Signed-off-by: Owen Hilyard <ohilyard@iol.unh.edu>
Acked-by: Vladimir Medvedkin <vladimir.medvedkin@intel.com>

Applied, thanks.
diff mbox series

Patch

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;
 }