[PATCH bpf-next] netdevsim: fix overflow on the error path

[Jakub Kicinski]

Undo loop condition on the error path would cause the i counter
to go below zero, if allocation failure happened with the first
(i.e. 0th) element of the array.

Fixes: 395cacb5f1a0 ("netdevsim: bpf: support fake map offload")
Reported-by: Dan Carpenter <dan.carpen...@oracle.com>
Signed-off-by: Jakub Kicinski <jakub.kicin...@netronome.com>
---
 drivers/net/netdevsim/bpf.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/net/netdevsim/bpf.c b/drivers/net/netdevsim/bpf.c
index de73c1ff0939..75c25306d234 100644
--- a/drivers/net/netdevsim/bpf.c
+++ b/drivers/net/netdevsim/bpf.c
@@ -480,8 +480,7 @@ static int
 nsim_bpf_map_alloc(struct netdevsim *ns, struct bpf_offloaded_map *offmap)
 {
        struct nsim_bpf_bound_map *nmap;
-       unsigned int i;
-       int err;
+       int i, err;
 
        if (WARN_ON(offmap->map.map_type != BPF_MAP_TYPE_ARRAY &&
                    offmap->map.map_type != BPF_MAP_TYPE_HASH))
@@ -518,7 +517,7 @@ nsim_bpf_map_alloc(struct netdevsim *ns, struct 
bpf_offloaded_map *offmap)
        return 0;
 
 err_free:
-       while (--i) {
+       while (--i >= 0) {
                kfree(nmap->entry[i].key);
                kfree(nmap->entry[i].value);
        }
-- 
2.15.1