From: Owen Hilyard <ohily...@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.
Signed-off-by: Owen Hilyard <ohily...@iol.unh.edu>
---
lib/rib/rte_rib6.c | 22 ++++++++++++++--------
1 file changed, 14 insertions(+), 8 deletions(-)
diff --git a/lib/rib/rte_rib6.c b/lib/rib/rte_rib6.c
index f6c55ee45..2de50449d 100644
--- a/lib/rib/rte_rib6.c
+++ b/lib/rib/rte_rib6.c
@@ -79,14 +79,20 @@ 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;
+ int 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 & 127) >> 3;
+ /*
+ * 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 *
--
2.30.2
