Messages in this thread | | | From | Li Zhong <> | Date | Sat, 17 Sep 2022 18:54:35 -0700 | Subject | Re: [PATCH v1] net/ipv4/nexthop: check the return value of nexthop_find_by_id() |
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On Sat, Sep 17, 2022 at 7:46 AM David Ahern <dsahern@kernel.org> wrote: > > On 9/17/22 2:29 AM, Nikolay Aleksandrov wrote: > > On 17/09/2022 05:30, Li Zhong wrote: > >> Check the return value of nexthop_find_by_id(), which could be NULL on > >> when not found. So we check to avoid null pointer dereference. > >> > >> Signed-off-by: Li Zhong <floridsleeves@gmail.com> > >> --- > >> net/ipv4/nexthop.c | 4 ++++ > >> 1 file changed, 4 insertions(+) > >> > >> diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c > >> index 853a75a8fbaf..9f91bb78eed5 100644 > >> --- a/net/ipv4/nexthop.c > >> +++ b/net/ipv4/nexthop.c > >> @@ -2445,6 +2445,10 @@ static struct nexthop *nexthop_create_group(struct net *net, > >> struct nh_info *nhi; > >> > >> nhe = nexthop_find_by_id(net, entry[i].id); > >> + if (!nhe) { > >> + err = -EINVAL; > >> + goto out_no_nh; > >> + } > >> if (!nexthop_get(nhe)) { > >> err = -ENOENT; > >> goto out_no_nh; > > > > These are validated in nh_check_attr_group() and should exist at this point. > > Since remove_nexthop() should run under rtnl I don't see a way for a nexthop > > to disappear after nh_check_attr_group() and before nexthop_create_group(). > > > > exactly. That lookup can't fail because the ids have been validated and > all of this is under rtnl preventing nexthop removes. >
Thanks for all your replies. That makes sense to me.
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