Commit 4d8f9065 authored by Pablo Neira Ayuso's avatar Pablo Neira Ayuso
Browse files

netfilter: nftables: clone set element expression template 



memcpy() breaks when using connlimit in set elements. Use
nft_expr_clone() to initialize the connlimit expression list, otherwise
connlimit garbage collector crashes when walking on the list head copy.

[  493.064656] Workqueue: events_power_efficient nft_rhash_gc [nf_tables]
[  493.064685] RIP: 0010:find_or_evict+0x5a/0x90 [nf_conncount]
[  493.064694] Code: 2b 43 40 83 f8 01 77 0d 48 c7 c0 f5 ff ff ff 44 39 63 3c 75 df 83 6d 18 01 48 8b 43 08 48 89 de 48 8b 13 48 8b 3d ee 2f 00 00 <48> 89 42 08 48 89 10 48 b8 00 01 00 00 00 00 ad de 48 89 03 48 83
[  493.064699] RSP: 0018:ffffc90000417dc0 EFLAGS: 00010297
[  493.064704] RAX: 0000000000000000 RBX: ffff888134f38410 RCX: 0000000000000000
[  493.064708] RDX: 0000000000000000 RSI: ffff888134f38410 RDI: ffff888100060cc0
[  493.064711] RBP: ffff88812ce594a8 R08: ffff888134f38438 R09: 00000000ebb9025c
[  493.064714] R10: ffffffff8219f838 R11: 0000000000000017 R12: 0000000000000001
[  493.064718] R13: ffffffff82146740 R14: ffff888134f38410 R15: 0000000000000000
[  493.064721] FS:  0000000000000000(0000) GS:ffff88840e440000(0000) knlGS:0000000000000000
[  493.064725] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  493.064729] CR2: 0000000000000008 CR3: 00000001330aa002 CR4: 00000000001706e0
[  493.064733] Call Trace:
[  493.064737]  nf_conncount_gc_list+0x8f/0x150 [nf_conncount]
[  493.064746]  nft_rhash_gc+0x106/0x390 [nf_tables]

Reported-by: default avatarLaura Garcia Liebana <nevola@gmail.com>
Fixes: 40944452 ("netfilter: nf_tables: add elements with stateful expressions")
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent b29c457a

net/netfilter/nf_tables_api.c

+34 −12
Original line number Diff line number Diff line
@@ -5295,18 +5295,37 @@ int nft_set_elem_expr_clone(const struct nft_ctx *ctx, struct nft_set *set, 
	return -ENOMEM;

}



static void nft_set_elem_expr_setup(const struct nft_set_ext *ext, int i,

				    struct nft_expr *expr_array[])

static int nft_set_elem_expr_setup(struct nft_ctx *ctx,

				   const struct nft_set_ext *ext,

				   struct nft_expr *expr_array[],

				   u32 num_exprs)

{

	struct nft_set_elem_expr *elem_expr = nft_set_ext_expr(ext);

	struct nft_expr *expr = nft_setelem_expr_at(elem_expr, elem_expr->size);

	struct nft_expr *expr;

	int i, err;



	for (i = 0; i < num_exprs; i++) {

		expr = nft_setelem_expr_at(elem_expr, elem_expr->size);

		err = nft_expr_clone(expr, expr_array[i]);

		if (err < 0)

			goto err_elem_expr_setup;



	memcpy(expr, expr_array[i], expr_array[i]->ops->size);

		elem_expr->size += expr_array[i]->ops->size;

	kfree(expr_array[i]);

		nft_expr_destroy(ctx, expr_array[i]);

		expr_array[i] = NULL;

	}



	return 0;



err_elem_expr_setup:

	for (; i < num_exprs; i++) {

		nft_expr_destroy(ctx, expr_array[i]);

		expr_array[i] = NULL;

	}



	return -ENOMEM;

}



static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,

			    const struct nlattr *attr, u32 nlmsg_flags)

{
@@ -5556,12 +5575,15 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set, 
		*nft_set_ext_obj(ext) = obj;

		obj->use++;

	}

	for (i = 0; i < num_exprs; i++)

		nft_set_elem_expr_setup(ext, i, expr_array);

	err = nft_set_elem_expr_setup(ctx, ext, expr_array, num_exprs);

	if (err < 0)

		goto err_elem_expr;



	trans = nft_trans_elem_alloc(ctx, NFT_MSG_NEWSETELEM, set);

	if (trans == NULL)

		goto err_trans;

	if (trans == NULL) {

		err = -ENOMEM;

		goto err_elem_expr;

	}



	ext->genmask = nft_genmask_cur(ctx->net) | NFT_SET_ELEM_BUSY_MASK;

	err = set->ops->insert(ctx->net, set, &elem, &ext2);
@@ -5605,7 +5627,7 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set, 
	set->ops->remove(ctx->net, set, &elem);

err_element_clash:

	kfree(trans);

err_trans:

err_elem_expr:

	if (obj)

		obj->use--;