From e38f95b700f6323fc5040e4d5b03180c19061a16 Mon Sep 17 00:00:00 2001 From: Vasily Averin Date: Sun, 20 Dec 2020 13:21:13 +0100 Subject: netfilter: ipset: fix shift-out-of-bounds in htable_bits() 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+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@syzkaller.appspotmail.com Signed-off-by: Vasily Averin Signed-off-by: Jozsef Kadlecsik --- kernel/net/netfilter/ipset/ip_set_hash_gen.h | 24 +++++------------------- 1 file changed, 5 insertions(+), 19 deletions(-) diff --git a/kernel/net/netfilter/ipset/ip_set_hash_gen.h b/kernel/net/netfilter/ipset/ip_set_hash_gen.h index 4a4062e..adf35fd 100644 --- a/kernel/net/netfilter/ipset/ip_set_hash_gen.h +++ b/kernel/net/netfilter/ipset/ip_set_hash_gen.h @@ -142,24 +142,6 @@ 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); - - /* We must fit both into u32 in jhash and size_t */ - if (bits >= 31) - return 31; - - 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]) @@ -1530,7 +1512,11 @@ 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); -- cgit v1.2.3