Commit a78cae24 authored by Jakub Kicinski's avatar Jakub Kicinski Committed by Daniel Borkmann
Browse files

xdp: Move the rxq_info.mem clearing to unreg_mem_model() 



xdp_rxq_info_unreg() implicitly calls xdp_rxq_info_unreg_mem_model().
This may well be confusing to the driver authors, and lead to double free
if they call xdp_rxq_info_unreg_mem_model() before xdp_rxq_info_unreg()
(when mem model type == MEM_TYPE_PAGE_POOL).

In fact error path of mvpp2_rxq_init() seems to currently do exactly that.

The double free will result in refcount underflow in page_pool_destroy().
Make the interface a little more programmer friendly by clearing type and
id so that xdp_rxq_info_unreg_mem_model() can be called multiple times.

Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210625221612.2637086-1-kuba@kernel.org
parent ccff81e1

net/core/xdp.c

+6 −5
Original line number Diff line number Diff line
@@ -113,8 +113,13 @@ static void mem_allocator_disconnect(void *allocator) 
void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq)

{

	struct xdp_mem_allocator *xa;

	int type = xdp_rxq->mem.type;

	int id = xdp_rxq->mem.id;



	/* Reset mem info to defaults */

	xdp_rxq->mem.id = 0;

	xdp_rxq->mem.type = 0;



	if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {

		WARN(1, "Missing register, driver bug");

		return;
@@ -123,7 +128,7 @@ void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq) 
	if (id == 0)

		return;



	if (xdp_rxq->mem.type == MEM_TYPE_PAGE_POOL) {

	if (type == MEM_TYPE_PAGE_POOL) {

		rcu_read_lock();

		xa = rhashtable_lookup(mem_id_ht, &id, mem_id_rht_params);

		page_pool_destroy(xa->page_pool);
@@ -144,10 +149,6 @@ void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq) 


	xdp_rxq->reg_state = REG_STATE_UNREGISTERED;

	xdp_rxq->dev = NULL;



	/* Reset mem info to defaults */

	xdp_rxq->mem.id = 0;

	xdp_rxq->mem.type = 0;

}

EXPORT_SYMBOL_GPL(xdp_rxq_info_unreg);