netdev - Re: [PATCH net 1/2] netfilter: nf_tables: avoid overflows in nft_hash

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Message-ID: <20210507075928.GA4320@salvia>
Date:   Fri, 7 May 2021 09:59:28 +0200
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     Jozsef Kadlecsik <kadlec@...ckhole.kfki.hu>,
        Florian Westphal <fw@...len.de>,
        netfilter-devel@...r.kernel.org, netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        syzbot <syzkaller@...glegroups.com>
Subject: Re: [PATCH net 1/2] netfilter: nf_tables: avoid overflows in
 nft_hash_buckets()

On Thu, May 06, 2021 at 05:53:23AM -0700, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@...gle.com>
> 
> Number of buckets being stored in 32bit variables, we have to
> ensure that no overflows occur in nft_hash_buckets()
> 
> syzbot injected a size == 0x40000000 and reported:
> 
> UBSAN: shift-out-of-bounds in ./include/linux/log2.h:57:13
> shift exponent 64 is too large for 64-bit type 'long unsigned int'
> CPU: 1 PID: 29539 Comm: syz-executor.4 Not tainted 5.12.0-rc7-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:79 [inline]
>  dump_stack+0x141/0x1d7 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:327
>  __roundup_pow_of_two include/linux/log2.h:57 [inline]
>  nft_hash_buckets net/netfilter/nft_set_hash.c:411 [inline]
>  nft_hash_estimate.cold+0x19/0x1e net/netfilter/nft_set_hash.c:652
>  nft_select_set_ops net/netfilter/nf_tables_api.c:3586 [inline]
>  nf_tables_newset+0xe62/0x3110 net/netfilter/nf_tables_api.c:4322
>  nfnetlink_rcv_batch+0xa09/0x24b0 net/netfilter/nfnetlink.c:488
>  nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:612 [inline]
>  nfnetlink_rcv+0x3af/0x420 net/netfilter/nfnetlink.c:630
>  netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline]
>  netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1338
>  netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1927
>  sock_sendmsg_nosec net/socket.c:654 [inline]
>  sock_sendmsg+0xcf/0x120 net/socket.c:674
>  ____sys_sendmsg+0x6e8/0x810 net/socket.c:2350
>  ___sys_sendmsg+0xf3/0x170 net/socket.c:2404
>  __sys_sendmsg+0xe5/0x1b0 net/socket.c:2433
>  do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46

Applied, thanks.