Re: [PATCH] netfilter: ipset: Fix maximal range check in hash_ipportnet4_uadt()

On Tue, Aug 03, 2021 at 12:18:13PM -0700, Nathan Chancellor wrote:

Clang warns:

net/netfilter/ipset/ip_set_hash_ipportnet.c:249:29: warning: variable
'port_to' is uninitialized when used here [-Wuninitialized]
        if (((u64)ip_to - ip + 1)*(port_to - port + 1) > IPSET_MAX_RANGE)
                                   ^~~~~~~
net/netfilter/ipset/ip_set_hash_ipportnet.c:167:45: note: initialize the
variable 'port_to' to silence this warning
        u32 ip = 0, ip_to = 0, p = 0, port, port_to;
                                                   ^
                                                    = 0
net/netfilter/ipset/ip_set_hash_ipportnet.c:249:39: warning: variable
'port' is uninitialized when used here [-Wuninitialized]
        if (((u64)ip_to - ip + 1)*(port_to - port + 1) > IPSET_MAX_RANGE)
                                             ^~~~
net/netfilter/ipset/ip_set_hash_ipportnet.c:167:36: note: initialize the
variable 'port' to silence this warning
        u32 ip = 0, ip_to = 0, p = 0, port, port_to;
                                          ^
                                           = 0
2 warnings generated.

The range check was added before port and port_to are initialized.
Shuffle the check after the initialization so that the check works
properly.

For the record: I have squashed this fix into the original patch in
nf.git to make it easier to pass it on to -stable.

Thanks.