[PATCH 0/1] zfcp bugfix for 7.2

[PATCH 0/1] zfcp bugfix for 7.2

[Nihar Panda]

Hi Martin and James,
we have a zfcp bugfix that address memory leak in zfcp.
It would be great if this could be included in v7.2 release.

Benjamin Block (1):
  fix memory leak during adapter release by destroying gid_pn_req

 drivers/s390/scsi/zfcp_aux.c | 1 +
 1 file changed, 1 insertion(+)

-- 
2.53.0

[PATCH 1/1] fix memory leak during adapter release by destroying gid_pn_req

[Nihar Panda]

From: Benjamin Block <bblock@linux.ibm.com>

When releasing an adapter we don't free the mempool `gid_pn_req` that is
allocated during the enqueue. This leaks memory:

  unreferenced object 0xd8d29297de700 (size 256):
    comm "(udev-worker)", pid 2105, jiffies 4294945794
    hex dump (first 32 bytes):
      00 00 00 00 de ad 4e ad ff ff ff ff 00 00 00 00  ......N.........
      ff ff ff ff ff ff ff ff 00 0d c4 5f 67 9d 99 e0  ..........._g...
    backtrace (crc 4a5b5da2):
      [<000dc45f64da418c>] kmemleak_alloc+0x6c/0xa0
      [<000dc45f62b430aa>] __kmalloc_cache_node_noprof+0x36a/0x4d0
      [<000dc45f629a535a>] mempool_create_node_noprof+0xaa/0x150
      [<000dc45ee2c065e6>] zfcp_allocate_low_mem_buffers+0x96/0x370 [zfcp]
      [<000dc45ee2c070f8>] zfcp_adapter_enqueue+0x598/0xd40 [zfcp]
      [<000dc45ee2c08eb0>] zfcp_ccw_set_online+0x160/0x210 [zfcp]
      [<000dc45f643d4762>] ccw_device_set_online+0x232/0xd80
      [<000dc45f643d53d4>] online_store_recog_and_online+0x124/0x390
      [<000dc45f643d8238>] online_store+0x298/0x5b0
      [<000dc45f62eb0a04>] kernfs_fop_write_iter+0x2c4/0x480
      [<000dc45f62c81150>] new_sync_write+0x370/0x4b0
      [<000dc45f62c87abe>] vfs_write+0x43e/0x5b0
      [<000dc45f62c87ff4>] ksys_write+0x114/0x1f0
      [<000dc45f621c4a16>] do_syscall+0x2f6/0x430
      [<000dc45f64d9d5d8>] __do_syscall+0xc8/0x1c0
      [<000dc45f64dc2224>] system_call+0x74/0xa0

Fix this by destroying the mempool during the adapter's release.

Fixes: 799b76d09aee ("[SCSI] zfcp: Decouple gid_pn requests from erp")
Signed-off-by: Benjamin Block <bblock@linux.ibm.com>
Tested-by: M Nikhil <nikh1092@linux.ibm.com>
Acked-by: M Nikhil <nikh1092@linux.ibm.com>
Reviewed-by: Chinmaya Kajagar <chinmayk@linux.ibm.com>
Reviewed-by: Nihar Panda <niharp@linux.ibm.com>
---
 drivers/s390/scsi/zfcp_aux.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/s390/scsi/zfcp_aux.c b/drivers/s390/scsi/zfcp_aux.c
index 8ff7db7921b5..fea573e00f9d 100644
--- a/drivers/s390/scsi/zfcp_aux.c
+++ b/drivers/s390/scsi/zfcp_aux.c
@@ -253,6 +253,7 @@ static int zfcp_allocate_low_mem_buffers(struct zfcp_adapter *adapter)
 static void zfcp_free_low_mem_buffers(struct zfcp_adapter *adapter)
 {
 	mempool_destroy(adapter->pool.erp_req);
+	mempool_destroy(adapter->pool.gid_pn_req);
 	mempool_destroy(adapter->pool.scsi_req);
 	mempool_destroy(adapter->pool.scsi_abort);
 	mempool_destroy(adapter->pool.qtcb_pool);
-- 
2.53.0

Re: [PATCH 1/1] fix memory leak during adapter release by destroying gid_pn_req

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] The error path in `zfcp_adapter_enqueue()` calls `zfcp_erp_thread_kill()` which unconditionally passes `adapter->erp_thread` to `kthread_stop()`. If adapter initialization fails before the thread is created (e.g., during `zfcp_allocate_low_mem_buffers()`), this results in a kernel panic because `kthread_stop()` does not handle NULL pointers.
--

--- Patch [1]: [PATCH 1/1] fix memory leak during adapter release by destroying gid_pn_req ---
commit 5b4668bd066d14a43f77f6f0301f8c98cbb5069c
Author: Benjamin Block <bblock@linux.ibm.com>

fix memory leak during adapter release by destroying gid_pn_req

When releasing an adapter we don't free the mempool gid_pn_req that is
allocated during the enqueue. This fixes the memory leak by destroying the
mempool during the adapter's release.

> diff --git a/drivers/s390/scsi/zfcp_aux.c b/drivers/s390/scsi/zfcp_aux.c
> index 8ff7db7921b5a..fea573e00f9df 100644
> --- a/drivers/s390/scsi/zfcp_aux.c
> +++ b/drivers/s390/scsi/zfcp_aux.c
> @@ -253,6 +253,7 @@ static int zfcp_allocate_low_mem_buffers(struct zfcp_adapter *adapter)
>  static void zfcp_free_low_mem_buffers(struct zfcp_adapter *adapter)
>  {
>  	mempool_destroy(adapter->pool.erp_req);
> +	mempool_destroy(adapter->pool.gid_pn_req);

[Severity: High]
This is a pre-existing issue, but if memory allocation fails during adapter
setup, could this lead to a kernel panic?

In zfcp_adapter_enqueue(), if zfcp_allocate_low_mem_buffers() returns -ENOMEM,
the code jumps to the failed label and unconditionally calls
zfcp_erp_thread_kill():

drivers/s390/scsi/zfcp_aux.c:zfcp_adapter_enqueue() {
    ...
failed:
    /* TODO: make this more fine-granular */
    cancel_delayed_work_sync(&adapter->scan_work);
    cancel_work_sync(&adapter->stat_work);
    cancel_work_sync(&adapter->ns_up_work);
    cancel_work_sync(&adapter->version_change_lost_work);
    zfcp_destroy_adapter_work_queue(adapter);

    zfcp_fc_wka_ports_force_offline(adapter->gs);
    zfcp_scsi_adapter_unregister(adapter);

    zfcp_erp_thread_kill(adapter);
    ...
}

However, if the thread was never created, adapter->erp_thread is NULL.
zfcp_erp_thread_kill() unconditionally passes it to kthread_stop():

drivers/s390/scsi/zfcp_erp.c:zfcp_erp_thread_kill() {
    kthread_stop(adapter->erp_thread);
    adapter->erp_thread = NULL;
}

Since kthread_stop() does not handle NULL pointers, will this result in a
NULL pointer dereference?

>  	mempool_destroy(adapter->pool.scsi_req);
>  	mempool_destroy(adapter->pool.scsi_abort);

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260720072736.3381816-2-niharp@linux.ibm.com?part=1

Re: [PATCH 1/1] fix memory leak during adapter release by destroying gid_pn_req

[Nihar Ranjan Panda]

Hi Martin and James,
The bug reported by the sashiko bot is a pre-existing issue and was not introduced by this fix.
 
Please allow this fix to go upstream. We will create an EWM ticket to address the bot's finding in a separate patch.

On 20/07/26 1:10 pm, sashiko-bot@kernel.org wrote:
> Pre-existing issues:
> - [High] The error path in `zfcp_adapter_enqueue()` calls `zfcp_erp_thread_kill()` which unconditionally passes `adapter->erp_thread` to `kthread_stop()`. If adapter initialization fails before the thread is created (e.g., during `zfcp_allocate_low_mem_buffers()`), this results in a kernel panic because `kthread_stop()` does not handle NULL pointers.
> --
> 
> --- Patch [1]: [PATCH 1/1] fix memory leak during adapter release by destroying gid_pn_req ---
> commit 5b4668bd066d14a43f77f6f0301f8c98cbb5069c
> Author: Benjamin Block <bblock@linux.ibm.com>
> 
> fix memory leak during adapter release by destroying gid_pn_req