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author | Jason Gunthorpe <jgg@mellanox.com> | 2020-01-13 14:33:10 +0000 |
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committer | Jason Gunthorpe <jgg@mellanox.com> | 2020-01-13 16:17:18 -0400 |
commit | 8bdf9dd984c18375d1090ddeb1792511f619c5c1 (patch) | |
tree | f5fe75a0e22cc09ccb4518668d5525dddc60f796 | |
parent | 3f59b6c3e600f9665dcf5b8e566cd7b778f03045 (diff) | |
download | linux-8bdf9dd984c18375d1090ddeb1792511f619c5c1.tar.bz2 |
RDMA/uverbs: Remove needs_kfree_rcu from uverbs_obj_type_class
After device disassociation the uapi_objects are destroyed and freed,
however it is still possible that core code can be holding a kref on the
uobject. When it finally goes to uverbs_uobject_free() via the kref_put()
it can trigger a use-after-free on the uapi_object.
Since needs_kfree_rcu is a micro optimization that only benefits file
uobjects, just get rid of it. There is no harm in using kfree_rcu even if
it isn't required, and the number of involved objects is small.
Link: https://lore.kernel.org/r/20200113143306.GA28717@ziepe.ca
Signed-off-by: Michael Guralnik <michaelgur@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
-rw-r--r-- | drivers/infiniband/core/rdma_core.c | 23 | ||||
-rw-r--r-- | include/rdma/uverbs_types.h | 1 |
2 files changed, 1 insertions, 23 deletions
diff --git a/drivers/infiniband/core/rdma_core.c b/drivers/infiniband/core/rdma_core.c index 6c72773faf29..17bdbe38fdfa 100644 --- a/drivers/infiniband/core/rdma_core.c +++ b/drivers/infiniband/core/rdma_core.c @@ -49,13 +49,7 @@ void uverbs_uobject_get(struct ib_uobject *uobject) static void uverbs_uobject_free(struct kref *ref) { - struct ib_uobject *uobj = - container_of(ref, struct ib_uobject, ref); - - if (uobj->uapi_object->type_class->needs_kfree_rcu) - kfree_rcu(uobj, rcu); - else - kfree(uobj); + kfree_rcu(container_of(ref, struct ib_uobject, ref), rcu); } void uverbs_uobject_put(struct ib_uobject *uobject) @@ -744,20 +738,6 @@ const struct uverbs_obj_type_class uverbs_idr_class = { .lookup_put = lookup_put_idr_uobject, .destroy_hw = destroy_hw_idr_uobject, .remove_handle = remove_handle_idr_uobject, - /* - * When we destroy an object, we first just lock it for WRITE and - * actually DESTROY it in the finalize stage. So, the problematic - * scenario is when we just started the finalize stage of the - * destruction (nothing was executed yet). Now, the other thread - * fetched the object for READ access, but it didn't lock it yet. - * The DESTROY thread continues and starts destroying the object. - * When the other thread continue - without the RCU, it would - * access freed memory. However, the rcu_read_lock delays the free - * until the rcu_read_lock of the READ operation quits. Since the - * exclusive lock of the object is still taken by the DESTROY flow, the - * READ operation will get -EBUSY and it'll just bail out. - */ - .needs_kfree_rcu = true, }; EXPORT_SYMBOL(uverbs_idr_class); @@ -920,7 +900,6 @@ const struct uverbs_obj_type_class uverbs_fd_class = { .lookup_put = lookup_put_fd_uobject, .destroy_hw = destroy_hw_fd_uobject, .remove_handle = remove_handle_fd_uobject, - .needs_kfree_rcu = false, }; EXPORT_SYMBOL(uverbs_fd_class); diff --git a/include/rdma/uverbs_types.h b/include/rdma/uverbs_types.h index d57a5ba00c74..0b0f5a5f392d 100644 --- a/include/rdma/uverbs_types.h +++ b/include/rdma/uverbs_types.h @@ -98,7 +98,6 @@ struct uverbs_obj_type_class { enum rdma_remove_reason why, struct uverbs_attr_bundle *attrs); void (*remove_handle)(struct ib_uobject *uobj); - u8 needs_kfree_rcu; }; struct uverbs_obj_type { |