Hi Jozsef, On Wed, Oct 26, 2022 at 02:26:08PM +0200, Jozsef Kadlecsik wrote: > Hi Daniel, > > On Tue, 25 Oct 2022, Daniel Xu wrote: > > > I'm following up with our hallway chat yesterday about how ipset > > hash:net,iface can easily OOM. > > > > Here's a quick reproducer (stolen from > > https://bugzilla.kernel.org/show_bug.cgi?id=199107): > > > > $ ipset create ACL.IN.ALL_PERMIT hash:net,iface hashsize 1048576 timeout 0 > > $ for i in $(seq 0 100); do /sbin/ipset add ACL.IN.ALL_PERMIT 0.0.0.0/0,kaf_$i timeout 0 -exist; done > > > > This used to cause a NULL ptr deref panic before > > https://github.com/torvalds/linux/commit/2b33d6ffa9e38f344418976b06 . > > > > Now it'll either allocate a huge amount of memory or fail a > > vmalloc(): > > > > [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 > > <...> > > > > Note that this behavior is somewhat documented > > (https://ipset.netfilter.org/ipset.man.html): > > > > > 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. > > > > I'm not sure how hard it would be to enforce a limit, but I think it would > > be a bit better to error than allocate many GBs of memory. > > That's a bug, actually the limit is not enforced in spite of the > documentation. The next patch fixes it and I'm going to submit to Pablo: > > diff --git a/net/netfilter/ipset/ip_set_hash_gen.h b/net/netfilter/ipset/ip_set_hash_gen.h > index 6e391308431d..3f8853ed32e9 100644 > --- a/net/netfilter/ipset/ip_set_hash_gen.h > +++ b/net/netfilter/ipset/ip_set_hash_gen.h > @@ -61,10 +61,6 @@ tune_bucketsize(u8 curr, u32 multi) > */ > return n > curr && n <= AHASH_MAX_TUNED ? n : curr; > } > -#define TUNE_BUCKETSIZE(h, multi) \ > - ((h)->bucketsize = tune_bucketsize((h)->bucketsize, multi)) > -#else > -#define TUNE_BUCKETSIZE(h, multi) > #endif > > /* A hash bucket */ > @@ -936,7 +932,11 @@ mtype_add(struct ip_set *set, void *value, const struct ip_set_ext *ext, > goto set_full; > /* Create a new slot */ > if (n->pos >= n->size) { > - TUNE_BUCKETSIZE(h, multi); > +#ifdef IP_SET_HASH_WITH_MULTI > + if (h->bucketsize >= AHASH_MAX_TUNED) > + goto set_full; > + h->bucketsize = tune_bucketsize(h->bucketsize, multi); > +#endif > if (n->size >= AHASH_MAX(h)) { > /* Trigger rehashing */ > mtype_data_next(&h->next, d); > > Best regards, > Jozsef > - > E-mail : kadlec@xxxxxxxxxxxxxxxxx, kadlecsik.jozsef@xxxxxxxxx > PGP key : https://wigner.hu/~kadlec/pgp_public_key.txt > Address : Wigner Research Centre for Physics > H-1525 Budapest 114, POB. 49, Hungary Thank you! Daniel
