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RDMA/iwcm: Fix use-after-free of work objects after cm_id destruction

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commit 6883b680e703c6b2efddb4e7a8d891ce1803d06b upstream.

The commit 59c68ac31e ("iw_cm: free cm_id resources on the last
deref") simplified cm_id resource management by freeing cm_id once all
references to the cm_id were removed. The references are removed either
upon completion of iw_cm event handlers or when the application destroys
the cm_id. This commit introduced the use-after-free condition where
cm_id_private object could still be in use by event handler works during
the destruction of cm_id. The commit aee2424246f9 ("RDMA/iwcm: Fix a
use-after-free related to destroying CM IDs") addressed this use-after-
free by flushing all pending works at the cm_id destruction.

However, still another use-after-free possibility remained. It happens
with the work objects allocated for each cm_id_priv within
alloc_work_entries() during cm_id creation, and subsequently freed in
dealloc_work_entries() once all references to the cm_id are removed.
If the cm_id's last reference is decremented in the event handler work,
the work object for the work itself gets removed, and causes the use-
after-free BUG below:

  BUG: KASAN: slab-use-after-free in __pwq_activate_work+0x1ff/0x250
  Read of size 8 at addr ffff88811f9cf800 by task kworker/u16:1/147091

  CPU: 2 UID: 0 PID: 147091 Comm: kworker/u16:1 Not tainted 6.15.0-rc2+ #27 PREEMPT(voluntary)
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-3.fc41 04/01/2014
  Workqueue:  0x0 (iw_cm_wq)
  Call Trace:
   <TASK>
   dump_stack_lvl+0x6a/0x90
   print_report+0x174/0x554
   ? __virt_addr_valid+0x208/0x430
   ? __pwq_activate_work+0x1ff/0x250
   kasan_report+0xae/0x170
   ? __pwq_activate_work+0x1ff/0x250
   __pwq_activate_work+0x1ff/0x250
   pwq_dec_nr_in_flight+0x8c5/0xfb0
   process_one_work+0xc11/0x1460
   ? __pfx_process_one_work+0x10/0x10
   ? assign_work+0x16c/0x240
   worker_thread+0x5ef/0xfd0
   ? __pfx_worker_thread+0x10/0x10
   kthread+0x3b0/0x770
   ? __pfx_kthread+0x10/0x10
   ? rcu_is_watching+0x11/0xb0
   ? _raw_spin_unlock_irq+0x24/0x50
   ? rcu_is_watching+0x11/0xb0
   ? __pfx_kthread+0x10/0x10
   ret_from_fork+0x30/0x70
   ? __pfx_kthread+0x10/0x10
   ret_from_fork_asm+0x1a/0x30
   </TASK>

  Allocated by task 147416:
   kasan_save_stack+0x2c/0x50
   kasan_save_track+0x10/0x30
   __kasan_kmalloc+0xa6/0xb0
   alloc_work_entries+0xa9/0x260 [iw_cm]
   iw_cm_connect+0x23/0x4a0 [iw_cm]
   rdma_connect_locked+0xbfd/0x1920 [rdma_cm]
   nvme_rdma_cm_handler+0x8e5/0x1b60 [nvme_rdma]
   cma_cm_event_handler+0xae/0x320 [rdma_cm]
   cma_work_handler+0x106/0x1b0 [rdma_cm]
   process_one_work+0x84f/0x1460
   worker_thread+0x5ef/0xfd0
   kthread+0x3b0/0x770
   ret_from_fork+0x30/0x70
   ret_from_fork_asm+0x1a/0x30

  Freed by task 147091:
   kasan_save_stack+0x2c/0x50
   kasan_save_track+0x10/0x30
   kasan_save_free_info+0x37/0x60
   __kasan_slab_free+0x4b/0x70
   kfree+0x13a/0x4b0
   dealloc_work_entries+0x125/0x1f0 [iw_cm]
   iwcm_deref_id+0x6f/0xa0 [iw_cm]
   cm_work_handler+0x136/0x1ba0 [iw_cm]
   process_one_work+0x84f/0x1460
   worker_thread+0x5ef/0xfd0
   kthread+0x3b0/0x770
   ret_from_fork+0x30/0x70
   ret_from_fork_asm+0x1a/0x30

  Last potentially related work creation:
   kasan_save_stack+0x2c/0x50
   kasan_record_aux_stack+0xa3/0xb0
   __queue_work+0x2ff/0x1390
   queue_work_on+0x67/0xc0
   cm_event_handler+0x46a/0x820 [iw_cm]
   siw_cm_upcall+0x330/0x650 [siw]
   siw_cm_work_handler+0x6b9/0x2b20 [siw]
   process_one_work+0x84f/0x1460
   worker_thread+0x5ef/0xfd0
   kthread+0x3b0/0x770
   ret_from_fork+0x30/0x70
   ret_from_fork_asm+0x1a/0x30

This BUG is reproducible by repeating the blktests test case nvme/061
for the rdma transport and the siw driver.

To avoid the use-after-free of cm_id_private work objects, ensure that
the last reference to the cm_id is decremented not in the event handler
works, but in the cm_id destruction context. For that purpose, move
iwcm_deref_id() call from destroy_cm_id() to the callers of
destroy_cm_id(). In iw_destroy_cm_id(), call iwcm_deref_id() after
flushing the pending works.

During the fix work, I noticed that iw_destroy_cm_id() is called from
cm_work_handler() and process_event() context. However, the comment of
iw_destroy_cm_id() notes that the function "cannot be called by the
event thread". Drop the false comment.

Closes: https://lore.kernel.org/linux-rdma/r5676e754sv35aq7cdsqrlnvyhiq5zktteaurl7vmfih35efko@z6lay7uypy3c/
Fixes: 59c68ac31e ("iw_cm: free cm_id resources on the last deref")
Cc: stable@vger.kernel.org
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Link: https://patch.msgid.link/20250510101036.1756439-1-shinichiro.kawasaki@wdc.com
Reviewed-by: Zhu Yanjun <yanjun.zhu@linux.dev>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Shin'ichiro Kawasaki
2025-05-10 19:10:36 +09:00
committed by Greg Kroah-Hartman
parent 442e80dcf6
commit 23a707bbcb
1 changed files with 15 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files

29
drivers/infiniband/core/iwcm.c
View File

@@ -367,12 +367,9 @@ EXPORT_SYMBOL(iw_cm_disconnect);
/* /*
* CM_ID <-- DESTROYING * CM_ID <-- DESTROYING
* *
* Clean up all resources associated with the connection and release * Clean up all resources associated with the connection.
* the initial reference taken by iw_create_cm_id.
*
* Returns true if and only if the last cm_id_priv reference has been dropped.
*/ */
static bool destroy_cm_id(struct iw_cm_id *cm_id) static void destroy_cm_id(struct iw_cm_id *cm_id)
{ {
struct iwcm_id_private *cm_id_priv; struct iwcm_id_private *cm_id_priv;
struct ib_qp *qp; struct ib_qp *qp;
@@ -441,20 +438,22 @@ static bool destroy_cm_id(struct iw_cm_id *cm_id)
iwpm_remove_mapinfo(&cm_id->local_addr, &cm_id->m_local_addr); iwpm_remove_mapinfo(&cm_id->local_addr, &cm_id->m_local_addr);
iwpm_remove_mapping(&cm_id->local_addr, RDMA_NL_IWCM); iwpm_remove_mapping(&cm_id->local_addr, RDMA_NL_IWCM);
} }
return iwcm_deref_id(cm_id_priv);
} }
/* /*
* This function is only called by the application thread and cannot * Destroy cm_id. If the cm_id still has other references, wait for all
* be called by the event thread. The function will wait for all * references to be released on the cm_id and then release the initial
* references to be released on the cm_id and then kfree the cm_id * reference taken by iw_create_cm_id.
* object.
*/ */
void iw_destroy_cm_id(struct iw_cm_id *cm_id) void iw_destroy_cm_id(struct iw_cm_id *cm_id)
{ {
if (!destroy_cm_id(cm_id)) struct iwcm_id_private *cm_id_priv;
cm_id_priv = container_of(cm_id, struct iwcm_id_private, id);
destroy_cm_id(cm_id);
if (refcount_read(&cm_id_priv->refcount) > 1)
flush_workqueue(iwcm_wq); flush_workqueue(iwcm_wq);
iwcm_deref_id(cm_id_priv);
} }
EXPORT_SYMBOL(iw_destroy_cm_id); EXPORT_SYMBOL(iw_destroy_cm_id);
@@ -1037,8 +1036,10 @@ static void cm_work_handler(struct work_struct *_work)
if (!test_bit(IWCM_F_DROP_EVENTS, &cm_id_priv->flags)) { if (!test_bit(IWCM_F_DROP_EVENTS, &cm_id_priv->flags)) {
ret = process_event(cm_id_priv, &levent); ret = process_event(cm_id_priv, &levent);
if (ret) if (ret) {
WARN_ON_ONCE(destroy_cm_id(&cm_id_priv->id)); destroy_cm_id(&cm_id_priv->id);
WARN_ON_ONCE(iwcm_deref_id(cm_id_priv));
}
} else } else
pr_debug("dropping event %d\n", levent.event); pr_debug("dropping event %d\n", levent.event);
if (iwcm_deref_id(cm_id_priv)) if (iwcm_deref_id(cm_id_priv))