netfilter: nf_tables: fix oob access

[ Upstream commit 3e38df1 ] BUG: KASAN: slab-out-of-bounds in nf_tables_rule_destroy+0xf1/0x130 at addr ffff88006a4c35c8 Read of size 8 by task nft/1607 When we've destroyed last valid expr, nft_expr_next() returns an invalid expr. We must not dereference it unless it passes != nft_expr_last() check. Signed-off-by: Florian Westphal <[email protected]> Signed-off-by: Pablo Neira Ayuso <[email protected]> Signed-off-by: Sasha Levin <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
klaby · Nov 30, 2017 · 0117c75 · 0117c75
1 parent ea13fd4
commit 0117c75
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
@@ -2068,7 +2068,7 @@ static void nf_tables_rule_destroy(const struct nft_ctx *ctx,
 	 * is called on error from nf_tables_newrule().
 	 */
 	expr = nft_expr_first(rule);
-	while (expr->ops && expr != nft_expr_last(rule)) {
+	while (expr != nft_expr_last(rule) && expr->ops) {
 		nf_tables_expr_destroy(ctx, expr);
 		expr = nft_expr_next(expr);
 	}