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Message-Id: <20201218120409.3659-5-pablo@netfilter.org>
Date: Fri, 18 Dec 2020 13:04:09 +0100
From: Pablo Neira Ayuso <pablo@...filter.org>
To: netfilter-devel@...r.kernel.org
Cc: davem@...emloft.net, netdev@...r.kernel.org, kuba@...nel.org
Subject: [PATCH net 4/4] netfilter: ipset: fix shift-out-of-bounds in htable_bits()
From: Vasily Averin <vvs@...tuozzo.com>
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@...kaller.appspotmail.com
Signed-off-by: Vasily Averin <vvs@...tuozzo.com>
Acked-by: Jozsef Kadlecsik <kadlec@...filter.org>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
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 1e7dddf824ae..6186358eac7c 100644
--- a/net/netfilter/ipset/ip_set_hash_gen.h
+++ b/net/netfilter/ipset/ip_set_hash_gen.h
@@ -141,20 +141,6 @@ htable_size(u8 hbits)
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])
@@ -1525,7 +1511,11 @@ IPSET_TOKEN(HTYPE, _create)(struct net *net, struct ip_set *set,
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);
--
2.20.1
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