On Thu, 17 Dec 2020, Vasily Averin wrote:
> htable_bits() can call jhash_size(32) and trigger shift-out-of-bounds
>
> UBSAN: shift-out-of-bounds in net/netfilter/ipset/ip_set_hash_gen.h:151:6
> shift exponent 32 is too large for 32-bit type 'unsigned int'
> CPU: 0 PID: 8498 Comm: syz-executor519
> Not tainted 5.10.0-rc7-next-20201208-syzkaller #0
> Call Trace:
> __dump_stack lib/dump_stack.c:79 [inline]
> dump_stack+0x107/0x163 lib/dump_stack.c:120
> ubsan_epilogue+0xb/0x5a lib/ubsan.c:148
> __ubsan_handle_shift_out_of_bounds.cold+0xb1/0x181 lib/ubsan.c:395
> htable_bits net/netfilter/ipset/ip_set_hash_gen.h:151 [inline]
> hash_mac_create.cold+0x58/0x9b net/netfilter/ipset/ip_set_hash_gen.h:1524
> ip_set_create+0x610/0x1380 net/netfilter/ipset/ip_set_core.c:1115
> nfnetlink_rcv_msg+0xecc/0x1180 net/netfilter/nfnetlink.c:252
> netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2494
> nfnetlink_rcv+0x1ac/0x420 net/netfilter/nfnetlink.c:600
> netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
> netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1330
> netlink_sendmsg+0x907/0xe40 net/netlink/af_netlink.c:1919
> sock_sendmsg_nosec net/socket.c:652 [inline]
> sock_sendmsg+0xcf/0x120 net/socket.c:672
> ____sys_sendmsg+0x6e8/0x810 net/socket.c:2345
> ___sys_sendmsg+0xf3/0x170 net/socket.c:2399
> __sys_sendmsg+0xe5/0x1b0 net/socket.c:2432
> do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
> entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
> This patch replaces htable_bits() by simple fls(hashsize - 1) call:
> it alone returns valid nbits both for round and non-round hashsizes.
> It is normal to set any nbits here because it is validated inside
> following htable_size() call which returns 0 for nbits>31.
>
> Fixes: 1feab10d7e6d("netfilter: ipset: Unified hash type generation")
> Reported-by: syzbot+d66bfadebca46cf61a2b@xxxxxxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Vasily Averin <vvs@xxxxxxxxxxxxx>
Acked-by: Jozsef Kadlecsik <kadlec@xxxxxxxxxxxxx>
Best regards,
Jozsef
> ---
> net/netfilter/ipset/ip_set_hash_gen.h | 20 +++++---------------
> 1 file changed, 5 insertions(+), 15 deletions(-)
>
> diff --git a/net/netfilter/ipset/ip_set_hash_gen.h b/net/netfilter/ipset/ip_set_hash_gen.h
> index 521e970..7d01086 100644
> --- a/net/netfilter/ipset/ip_set_hash_gen.h
> +++ b/net/netfilter/ipset/ip_set_hash_gen.h
> @@ -143,20 +143,6 @@ struct net_prefixes {
> return hsize * sizeof(struct hbucket *) + sizeof(struct htable);
> }
>
> -/* Compute htable_bits from the user input parameter hashsize */
> -static u8
> -htable_bits(u32 hashsize)
> -{
> - /* Assume that hashsize == 2^htable_bits */
> - u8 bits = fls(hashsize - 1);
> -
> - if (jhash_size(bits) != hashsize)
> - /* Round up to the first 2^n value */
> - bits = fls(hashsize);
> -
> - return bits;
> -}
> -
> #ifdef IP_SET_HASH_WITH_NETS
> #if IPSET_NET_COUNT > 1
> #define __CIDR(cidr, i) (cidr[i])
> @@ -1520,7 +1506,11 @@ struct mtype_resize_ad {
> if (!h)
> return -ENOMEM;
>
> - hbits = htable_bits(hashsize);
> + /* Compute htable_bits from the user input parameter hashsize.
> + * Assume that hashsize == 2^htable_bits,
> + * otherwise round up to the first 2^n value.
> + */
> + hbits = fls(hashsize - 1);
> hsize = htable_size(hbits);
> if (hsize == 0) {
> kfree(h);
> --
> 1.8.3.1
>
>
-
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
