From 235ef2d0e750885c29340b0fc40620a7a4f52e12 Mon Sep 17 00:00:00 2001 From: Patrisious Haddad Date: Mon, 13 Jul 2026 18:38:04 +0300 Subject: [PATCH] RDMA/core: Fix potential use after free in counter_release() When accessing a counter via the netlink path the only synchronization mechanism for the said counter is rdma_restrack_get(). Currently, rdma_restrack_del() is invoked at the end of counter_release(), which is too late, since by that point vendor-specific resources associated with the counter might already be freed. This can leave a short window where the counter remains accessible through restrack, leading to a potential use-after-free. Fix this by moving the rdma_restrack_del() call to be before the freeing of the vendor-specific resources, ensuring that the counter is removed from restrack before its internal resources are released. This guarantees that no new users hold references to a counter that is in the process of destruction. Fixes: 99fa331dc862 ("RDMA/counter: Add "auto" configuration mode support") Signed-off-by: Patrisious Haddad Reviewed-by: Michael Guralnik Signed-off-by: Edward Srouji Link: https://patch.msgid.link/20260713-restrack-uaf-fix-resub-v2-5-bbe8bb270d51@nvidia.com Signed-off-by: Leon Romanovsky --- drivers/infiniband/core/counters.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/infiniband/core/counters.c b/drivers/infiniband/core/counters.c index a9e189194c13..a2c85840c501 100644 --- a/drivers/infiniband/core/counters.c +++ b/drivers/infiniband/core/counters.c @@ -234,7 +234,6 @@ static void rdma_counter_free(struct rdma_counter *counter) mutex_unlock(&port_counter->lock); - rdma_restrack_del(&counter->res); rdma_free_hw_stats_struct(counter->stats); kfree(counter); } @@ -329,6 +328,7 @@ static void counter_release(struct kref *kref) counter = container_of(kref, struct rdma_counter, kref); counter_history_stat_update(counter); + rdma_restrack_del(&counter->res); counter->device->ops.counter_dealloc(counter); rdma_counter_free(counter); } @@ -490,7 +490,8 @@ static struct rdma_counter *rdma_get_counter_by_id(struct ib_device *dev, return NULL; counter = container_of(res, struct rdma_counter, res); - kref_get(&counter->kref); + if (!kref_get_unless_zero(&counter->kref)) + counter = NULL; rdma_restrack_put(res); return counter;