[PATCH 5.11 082/122] netfilter: nftables: clone set element expression template

Greg Kroah-Hartman
2021-04-19T13:13:20Z

From: Pablo Neira Ayuso <pablo@netfilter.org>

commit 4d8f9065830e526c83199186c5f56a6514f457d2 upstream.

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: Laura Garcia Liebana <nevola@gmail.com>
Fixes: 409444522976 ("netfilter: nf_tables: add elements with stateful expressions")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/netfilter/nf_tables_api.c | 46 +++++++++++++++++++++++++++++++-----------
1 file changed, 34 insertions(+), 12 deletions(-)

--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -5263,16 +5263,35 @@ err_expr:
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;

- memcpy(expr, expr_array[i], expr_array[i]->ops->size);
- elem_expr->size += expr_array[i]->ops->size;
- kfree(expr_array[i]);
- expr_array[i] = NULL;
+ 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;
+
+ elem_expr->size += expr_array[i]->ops->size;
+ 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,
@@ -5524,12 +5543,15 @@ static int nft_add_set_elem(struct nft_c
*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);
@@ -5573,7 +5595,7 @@ err_set_full:
set->ops->remove(ctx->net, set, &elem);
err_element_clash:
kfree(trans);
-err_trans:
+err_elem_expr:
if (obj)
obj->use--;