netfilter: nf_tables: initialize set before expression setup

commit ad9f151e560b016b6ad3280b48e42fa11e1a5440 upstream.

nft_set_elem_expr_alloc() needs an initialized set if expression sets on
the NFT_EXPR_GC flag. Move set fields initialization before expression
setup.

[4512935.019450] ==================================================================
[4512935.019456] BUG: KASAN: null-ptr-deref in nft_set_elem_expr_alloc+0x84/0xd0 [nf_tables]
[4512935.019487] Read of size 8 at addr 0000000000000070 by task nft/23532
[4512935.019494] CPU: 1 PID: 23532 Comm: nft Not tainted 5.12.0-rc4+ #48
[...]
[4512935.019502] Call Trace:
[4512935.019505]  dump_stack+0x89/0xb4
[4512935.019512]  ? nft_set_elem_expr_alloc+0x84/0xd0 [nf_tables]
[4512935.019536]  ? nft_set_elem_expr_alloc+0x84/0xd0 [nf_tables]
[4512935.019560]  kasan_report.cold.12+0x5f/0xd8
[4512935.019566]  ? nft_set_elem_expr_alloc+0x84/0xd0 [nf_tables]
[4512935.019590]  nft_set_elem_expr_alloc+0x84/0xd0 [nf_tables]
[4512935.019615]  nf_tables_newset+0xc7f/0x1460 [nf_tables]

Reported-by: syzbot+ce96ca2b1d0b37c6422d@syzkaller.appspotmail.com
Fixes: 65038428b2c6 ("netfilter: nf_tables: allow to specify stateful expression in set definition")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 947d52cff5829ff725f02881437ef734ef8078d1..3942a29413a40a976e9796601859760002ae418d 100644 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -4280,15 +4280,7 @@ static int nf_tables_newset(struct net *net, struct sock *nlsk,
        err = nf_tables_set_alloc_name(&ctx, set, name);
        kfree(name);
        if (err < 0)
-               goto err_set_alloc_name;
-
-       if (nla[NFTA_SET_EXPR]) {
-               expr = nft_set_elem_expr_alloc(&ctx, set, nla[NFTA_SET_EXPR]);
-               if (IS_ERR(expr)) {
-                       err = PTR_ERR(expr);
-                       goto err_set_alloc_name;
-               }
-       }
+               goto err_set_name;
 
        udata = NULL;
        if (udlen) {
@@ -4299,21 +4291,19 @@ static int nf_tables_newset(struct net *net, struct sock *nlsk,
        INIT_LIST_HEAD(&set->bindings);
        set->table = table;
        write_pnet(&set->net, net);
-       set->ops   = ops;
+       set->ops = ops;
        set->ktype = ktype;
-       set->klen  = desc.klen;
+       set->klen = desc.klen;
        set->dtype = dtype;
        set->objtype = objtype;
-       set->dlen  = desc.dlen;
-       set->expr = expr;
+       set->dlen = desc.dlen;
        set->flags = flags;
-       set->size  = desc.size;
+       set->size = desc.size;
        set->policy = policy;
-       set->udlen  = udlen;
-       set->udata  = udata;
+       set->udlen = udlen;
+       set->udata = udata;
        set->timeout = timeout;
        set->gc_int = gc_int;
-       set->handle = nf_tables_alloc_handle(table);
 
        set->field_count = desc.field_count;
        for (i = 0; i < desc.field_count; i++)
@@ -4323,20 +4313,32 @@ static int nf_tables_newset(struct net *net, struct sock *nlsk,
        if (err < 0)
                goto err_set_init;
 
+       if (nla[NFTA_SET_EXPR]) {
+               expr = nft_set_elem_expr_alloc(&ctx, set, nla[NFTA_SET_EXPR]);
+               if (IS_ERR(expr)) {
+                       err = PTR_ERR(expr);
+                       goto err_set_expr_alloc;
+               }
+
+               set->expr = expr;
+       }
+
+       set->handle = nf_tables_alloc_handle(table);
+
        err = nft_trans_set_add(&ctx, NFT_MSG_NEWSET, set);
        if (err < 0)
-               goto err_set_trans;
+               goto err_set_expr_alloc;
 
        list_add_tail_rcu(&set->list, &table->sets);
        table->use++;
        return 0;
 
-err_set_trans:
+err_set_expr_alloc:
+       if (set->expr)
+               nft_expr_destroy(&ctx, set->expr);
+
        ops->destroy(set);
 err_set_init:
-       if (expr)
-               nft_expr_destroy(&ctx, expr);
-err_set_alloc_name:
        kfree(set->name);
 err_set_name:
        kvfree(set);