In the Linux kernel, the following vulnerability has been resolved: scsi: qla2xxx: Fix queue teardown NULL dma_free and bitmap locking qla

In the Linux kernel, the following vulnerability has been resolved:

scsi: qla2xxx: Fix queue teardown NULL dma_free and bitmap locking

qla25xx_free_req_que() and qla25xx_free_rsp_que() have two pre-existing
bugs exposed on the error path of qla25xx_create_{req,rsp}_que():

1. When dma_alloc_coherent() fails during queue creation, the error
   path calls the free function with req->ring / rsp->ring still NULL
   (from kzalloc). The unconditional dma_free_coherent() with a NULL
   cpu_addr is undefined behavior and can panic.

2. The free functions clear req_qid_map / rsp_qid_map under vport_lock,
   but the create functions protect the same bitmaps with mq_lock.
   This provides no mutual exclusion. Additionally, the create error
   path clears the bit and releases mq_lock before calling the free
   function, creating a window where another thread can allocate the
   same que_id and have its ha->req_q_map entry clobbered by the
   subsequent lockless NULL assignment in the free function.

Fix by:

• Guarding dma_free_coherent() with a NULL check on the ring pointer.

• Using mq_lock (the lock held by all creators) in the free functions
  to atomically NULL the map entry and clear the bitmap bit.

• Removing the now-redundant clear_bit blocks from the create error
  paths since the free functions handle it atomically.