CVE-2022-49911

In the Linux kernel, the following vulnerability has been resolved:

netfilter: ipset: enforce documented limit to prevent allocating huge memory

Daniel Xu reported that the hash:net,iface type of the ipset subsystem does not limit adding the same network with different interfaces to a set, which can lead to huge memory usage or allocation failure.

The quick reproducer is

$ ipset create ACL.IN.ALLPERMIT hash:net,iface hashsize 1048576 timeout 0 $ for i in $(seq 0 100); do /sbin/ipset add ACL.IN.ALLPERMIT 0.0.0.0/0,kaf_$i timeout 0 -exist; done

The backtrace when vmalloc fails:

    [Tue Oct 25 00:13:08 2022] ipset: vmalloc error: size 1073741848, exceeds total pages
    <...>
    [Tue Oct 25 00:13:08 2022] Call Trace:
    [Tue Oct 25 00:13:08 2022]  <TASK>
    [Tue Oct 25 00:13:08 2022]  dump_stack_lvl+0x48/0x60
    [Tue Oct 25 00:13:08 2022]  warn_alloc+0x155/0x180
    [Tue Oct 25 00:13:08 2022]  __vmalloc_node_range+0x72a/0x760
    [Tue Oct 25 00:13:08 2022]  ? hash_netiface4_add+0x7c0/0xb20
    [Tue Oct 25 00:13:08 2022]  ? __kmalloc_large_node+0x4a/0x90
    [Tue Oct 25 00:13:08 2022]  kvmalloc_node+0xa6/0xd0
    [Tue Oct 25 00:13:08 2022]  ? hash_netiface4_resize+0x99/0x710
    <...>

The fix is to enforce the limit documented in the ipset(8) manpage:

The internal restriction of the hash:net,iface set type is that the same network prefix cannot be stored with more than 64 different interfaces in a single set.