[PATCH] net: microchip: vcap: stop scanning after deleting key field

[Harshit Mogalapalli]

The only call outside the KUnit tests is in
sparx5_tc_add_rule_copy(), which passes a fixed key list with no
duplicate entries. Therefore, the potential double-free is not
currently reachable in tree.

However, vcap_filter_rule_keys() is exported and does not require its
key list entries to be unique. If a future or external caller supplies
the same key at another position that the inner loop visits, it calls
list_del() and kfree() a second time on the freed field, leading to a
potential double-free.

Break the inner loop after removing a matching field. The outer safe
list traversal continues to process the remaining rule fields.

Fixes: 465a38a269e9 ("net: microchip: sparx5: Support for copying and modifying rules in the API")
Reported-by: Dan Carpenter <error27@xxxxxxxxx>
Closes: https://lore.kernel.org/all/ahs-lCAXXikkaHky@stanley.mountain/
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@xxxxxxxxxx>
---
 drivers/net/ethernet/microchip/vcap/vcap_api.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/microchip/vcap/vcap_api.c b/drivers/net/ethernet/microchip/vcap/vcap_api.c
index 788c0728d763..0f8d98f2094d 100644
--- a/drivers/net/ethernet/microchip/vcap/vcap_api.c
+++ b/drivers/net/ethernet/microchip/vcap/vcap_api.c
@@ -3527,8 +3527,8 @@ int vcap_filter_rule_keys(struct vcap_rule *rule,
 				if (key == keylist[idx]) {
 					list_del(&ckf->ctrl.list);
 					kfree(ckf);
-					idx++;
 					err = 0;
+					break;
 				}
 		}
 	}
-- 
2.52.0