From bded4de4a5e13036a1589e9d5939b4d420479c0d Mon Sep 17 00:00:00 2001 From: Saeed Mirzamohammadi Date: Tue, 20 Oct 2020 13:41:36 +0200 Subject: netfilter: nftables_offload: KASAN slab-out-of-bounds Read in nft_flow_rule_create commit 31cc578ae2de19c748af06d859019dced68e325d upstream. This patch fixes the issue due to: BUG: KASAN: slab-out-of-bounds in nft_flow_rule_create+0x622/0x6a2 net/netfilter/nf_tables_offload.c:40 Read of size 8 at addr ffff888103910b58 by task syz-executor227/16244 The error happens when expr->ops is accessed early on before performing the boundary check and after nft_expr_next() moves the expr to go out-of-bounds. This patch checks the boundary condition before expr->ops that fixes the slab-out-of-bounds Read issue. Add nft_expr_more() and use it to fix this problem. Signed-off-by: Saeed Mirzamohammadi Signed-off-by: Pablo Neira Ayuso Signed-off-by: Greg Kroah-Hartman --- include/net/netfilter/nf_tables.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include') diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h index bc2c73f54962..a576bcbba2fc 100644 --- a/include/net/netfilter/nf_tables.h +++ b/include/net/netfilter/nf_tables.h @@ -872,6 +872,12 @@ static inline struct nft_expr *nft_expr_last(const struct nft_rule *rule) return (struct nft_expr *)&rule->data[rule->dlen]; } +static inline bool nft_expr_more(const struct nft_rule *rule, + const struct nft_expr *expr) +{ + return expr != nft_expr_last(rule) && expr->ops; +} + static inline struct nft_userdata *nft_userdata(const struct nft_rule *rule) { return (void *)&rule->data[rule->dlen]; -- cgit v1.2.3