From: Phil Sutter <phil@nwl.cc>
Date: Wed, 11 Jun 2025 12:15:38 +0000 (+0200)
Subject: netlink: Do not allocate a bogus flowtable priority expr
X-Git-Url: http://git.ipfire.org/gitweb/gitweb.cgi?a=commitdiff_plain;h=567ca7659e1ee6c04b1652eb5df8ceeecd8ce2c9;p=thirdparty%2Fnftables.git

netlink: Do not allocate a bogus flowtable priority expr

commit 10b9a85b3278e0933bf47226588fede8c9fcbcc8 upstream.

Code accidentally treats missing NFTNL_FLOWTABLE_PRIO attribute as zero
prio value which may not be correct.

Fixes: db0697ce7f602 ("src: support for flowtable listing")
Signed-off-by: Phil Sutter <phil@nwl.cc>
Reviewed-by: Pablo Neira Ayuso <pablo@netfilter.org>
---

diff --git a/src/netlink.c b/src/netlink.c
index 508b6ea8..5c639881 100644
--- a/src/netlink.c
+++ b/src/netlink.c
@@ -1845,14 +1845,16 @@ netlink_delinearize_flowtable(struct netlink_ctx *ctx,
 		      sizeof(char *), qsort_device_cmp);
 	}
 
-	priority = nftnl_flowtable_get_u32(nlo, NFTNL_FLOWTABLE_PRIO);
-	flowtable->priority.expr =
+	if (nftnl_flowtable_is_set(nlo, NFTNL_FLOWTABLE_PRIO)) {
+		priority = nftnl_flowtable_get_u32(nlo, NFTNL_FLOWTABLE_PRIO);
+		flowtable->priority.expr =
 				constant_expr_alloc(&netlink_location,
 						    &integer_type,
 						    BYTEORDER_HOST_ENDIAN,
 						    sizeof(int) *
 						    BITS_PER_BYTE,
 						    &priority);
+	}
 	flowtable->hook.num =
 		nftnl_flowtable_get_u32(nlo, NFTNL_FLOWTABLE_HOOKNUM);
 	flowtable->flags =