| Message ID | 20210506125323.3887186-1-eric.dumazet@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [net,1/2] netfilter: nf_tables: avoid overflows in nft_hash_buckets() | expand |
On Thu, May 06, 2021 at 05:53:23AM -0700, Eric Dumazet wrote: > From: Eric Dumazet <edumazet@google.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.
diff --git a/net/netfilter/nft_set_hash.c b/net/netfilter/nft_set_hash.c index 58f576abcd4a7f22bb9d362550b98e79e2152af3..328f2ce32e4cbd772afe03a10f6d13a7ed6b93d5 100644 --- a/net/netfilter/nft_set_hash.c +++ b/net/netfilter/nft_set_hash.c @@ -412,9 +412,17 @@ static void nft_rhash_destroy(const struct nft_set *set) (void *)set); } +/* Number of buckets is stored in u32, so cap our result to 1U<<31 */ +#define NFT_MAX_BUCKETS (1U << 31) + static u32 nft_hash_buckets(u32 size) { - return roundup_pow_of_two(size * 4 / 3); + u64 val = div_u64((u64)size * 4, 3); + + if (val >= NFT_MAX_BUCKETS) + return NFT_MAX_BUCKETS; + + return roundup_pow_of_two(val); } static bool nft_rhash_estimate(const struct nft_set_desc *desc, u32 features,