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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: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210625221612.2637086-1-kuba@kernel.org
This commit is contained in:
Jakub Kicinski 2021-06-25 15:16:12 -07:00 committed by Daniel Borkmann
parent ccff81e1d0
commit a78cae2476
1 changed files with 6 additions and 5 deletions
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11
net/core/xdp.c
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@ -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);