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authorEric Dumazet <edumazet@google.com>2021-05-06 05:53:23 -0700
committerPablo Neira Ayuso <pablo@netfilter.org>2021-05-07 10:01:29 +0200
commita54754ec9891830ba548e2010c889e3c8146e449 (patch)
tree5806f69223da2a63bf2461b97985be43b3b23bc8
parent85dfd816fabfc16e71786eda0a33a7046688b5b0 (diff)
netfilter: nftables: avoid overflows in nft_hash_buckets()
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 Fixes: 0ed6389c483d ("netfilter: nf_tables: rename set implementations") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
-rw-r--r--net/netfilter/nft_set_hash.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/net/netfilter/nft_set_hash.c b/net/netfilter/nft_set_hash.c
index 58f576abcd4a..328f2ce32e4c 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,

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