netfilter: nftables: fix incorrect increment of loop counter

The intention of the err_expr cleanup path is to iterate over the
allocated expr_array objects and free them, starting from i - 1 and
working down to the start of the array. Currently the loop counter
is being incremented instead of decremented and also the index i is
being used instead of k, repeatedly destroying the same expr_array
element.  Fix this by decrementing k and using k as the index into
expr_array.

Addresses-Coverity: ("Infinite loop")
Fixes: 8cfd9b0f8515 ("netfilter: nftables: generalize set expressions support")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 8d5aa0a..4186b1e 100644 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -5254,8 +5254,8 @@ static int nft_set_elem_expr_clone(const struct nft_ctx *ctx,
        return 0;
 
 err_expr:
-       for (k = i - 1; k >= 0; k++)
-               nft_expr_destroy(ctx, expr_array[i]);
+       for (k = i - 1; k >= 0; k--)
+               nft_expr_destroy(ctx, expr_array[k]);
 
        return -ENOMEM;
 }