netfilter: nft_set_pipapo: fix improper element removal

stable inclusion
from stable-v5.10.188
commit 3a91099ecd59a42d1632fcb152bf7222f268ea2b
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I7P3TK
CVE: CVE-2023-4004

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3a91099ecd59a42d1632fcb152bf7222f268ea2b

---------------------------

[ Upstream commit 87b5a5c209405cb6b57424cdfa226a6dbd349232 ]

end key should be equal to start unless NFT_SET_EXT_KEY_END is present.

Its possible to add elements that only have a start key
("{ 1.0.0.0 . 2.0.0.0 }") without an internval end.

Insertion treats this via:

if (nft_set_ext_exists(ext, NFT_SET_EXT_KEY_END))
   end = (const u8 *)nft_set_ext_key_end(ext)->data;
else
   end = start;

but removal side always uses nft_set_ext_key_end().
This is wrong and leads to garbage remaining in the set after removal
next lookup/insert attempt will give:

BUG: KASAN: slab-use-after-free in pipapo_get+0x8eb/0xb90
Read of size 1 at addr ffff888100d50586 by task nft-pipapo_uaf_/1399
Call Trace:
 kasan_report+0x105/0x140
 pipapo_get+0x8eb/0xb90
 nft_pipapo_insert+0x1dc/0x1710
 nf_tables_newsetelem+0x31f5/0x4e00
 ..

Fixes: 3c4287f6 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Reported-by: Nlonial con <kongln9170@gmail.com>
Reviewed-by: NStefano Brivio <sbrivio@redhat.com>
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NLu Wei <luwei32@huawei.com>

net/netfilter/nft_set_pipapo.c

@@ -1904,7 +1904,11 @@ static void nft_pipapo_remove(const struct net *net, const struct nft_set *set,
 		int i, start, rules_fx;
 
 		match_start = data;
-		match_end = (const u8 *)nft_set_ext_key_end(&e->ext)->data;
+
+		if (nft_set_ext_exists(&e->ext, NFT_SET_EXT_KEY_END))
+			match_end = (const u8 *)nft_set_ext_key_end(&e->ext)->data;
+		else
+			match_end = data;
 
 		start = first_rule;
 		rules_fx = rules_f0;