[PATCH] fib: fix incorrect prefix addition handling

[PATCH] fib: fix incorrect prefix addition handling

[Vladimir Medvedkin]

When adding a prefix longer than /24 in FIB/FIB6 as a first prefix within
its corresponding /24 supernet with the same next hop as its parent, the
code would incorrectly skip incrementing the number of reserved TBL8 due
to an early return statement. This could lead to integer overflow in
'dp->rsvd_tbl8s'. This commit corrects the logic to ensure that the
reserved TBL8 count is properly incremented in such scenarios.

Bugzilla ID: 1731
Fixes: 7dc7868b200d ("fib: add DIR24-8 dataplane algorithm")
Fixes: c3e12e0f0354 ("fib: add dataplane algorithm for IPv6")
Cc: stable@dpdk.org

Signed-off-by: Vladimir Medvedkin <vladimir.medvedkin@intel.com>
---
 lib/fib/dir24_8.c | 3 ++-
 lib/fib/trie.c    | 4 ++--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/lib/fib/dir24_8.c b/lib/fib/dir24_8.c
index 2ba7e93511..1d99c8b21f 100644
--- a/lib/fib/dir24_8.c
+++ b/lib/fib/dir24_8.c
@@ -495,13 +495,14 @@ dir24_8_modify(struct rte_fib *fib, uint32_t ip, uint8_t depth,
 		if (parent != NULL) {
 			rte_rib_get_nh(parent, &par_nh);
 			if (par_nh == next_hop)
-				return 0;
+				goto successfully_added;
 		}
 		ret = modify_fib(dp, rib, ip, depth, next_hop);
 		if (ret != 0) {
 			rte_rib_remove(rib, ip, depth);
 			return ret;
 		}
+successfully_added:
 		if ((depth > 24) && (tmp == NULL))
 			dp->rsvd_tbl8s++;
 		return 0;
diff --git a/lib/fib/trie.c b/lib/fib/trie.c
index 24a08b827d..edb7442cb1 100644
--- a/lib/fib/trie.c
+++ b/lib/fib/trie.c
@@ -571,14 +571,14 @@ trie_modify(struct rte_fib6 *fib, const struct rte_ipv6_addr *ip,
 		if (parent != NULL) {
 			rte_rib6_get_nh(parent, &par_nh);
 			if (par_nh == next_hop)
-				return 0;
+				goto successfully_added;
 		}
 		ret = modify_dp(dp, rib, &ip_masked, depth, next_hop);
 		if (ret != 0) {
 			rte_rib6_remove(rib, &ip_masked, depth);
 			return ret;
 		}
-
+successfully_added:
 		dp->rsvd_tbl8s += depth_diff;
 		return 0;
 	case RTE_FIB6_DEL:
-- 
2.43.0

Re: [PATCH] fib: fix incorrect prefix addition handling

[Thomas Monjalon]

21/01/2026 18:57, Vladimir Medvedkin:
> When adding a prefix longer than /24 in FIB/FIB6 as a first prefix within
> its corresponding /24 supernet with the same next hop as its parent, the
> code would incorrectly skip incrementing the number of reserved TBL8 due
> to an early return statement. This could lead to integer overflow in
> 'dp->rsvd_tbl8s'. This commit corrects the logic to ensure that the
> reserved TBL8 count is properly incremented in such scenarios.
> 
> Bugzilla ID: 1731
> Fixes: 7dc7868b200d ("fib: add DIR24-8 dataplane algorithm")
> Fixes: c3e12e0f0354 ("fib: add dataplane algorithm for IPv6")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Vladimir Medvedkin <vladimir.medvedkin@intel.com>

Applied, thanks.