mm, treewide: rename kzfree() to kfree_sensitive()

As said by Linus:

  A symmetric naming is only helpful if it implies symmetries in use.
  Otherwise it's actively misleading.

  In "kzalloc()", the z is meaningful and an important part of what the
  caller wants.

  In "kzfree()", the z is actively detrimental, because maybe in the
  future we really _might_ want to use that "memfill(0xdeadbeef)" or
  something. The "zero" part of the interface isn't even _relevant_.

The main reason that kzfree() exists is to clear sensitive information
that should not be leaked to other future users of the same memory
objects.

Rename kzfree() to kfree_sensitive() to follow the example of the recently
added kvfree_sensitive() and make the intention of the API more explicit.
In addition, memzero_explicit() is used to clear the memory to make sure
that it won't get optimized away by the compiler.

The renaming is done by using the command sequence:

  git grep -w --name-only kzfree |\
  xargs sed -i 's/kzfree/kfree_sensitive/'

followed by some editing of the kfree_sensitive() kerneldoc and adding
a kzfree backward compatibility macro in slab.h.

[akpm@linux-foundation.org: fs/crypto/inline_crypt.c needs linux/slab.h]
[akpm@linux-foundation.org: fix fs/crypto/inline_crypt.c some more]

Suggested-by: Joe Perches <joe@perches.com>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: David Howells <dhowells@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: James Morris <jmorris@namei.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Joe Perches <joe@perches.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Jason A . Donenfeld" <Jason@zx2c4.com>
Link: http://lkml.kernel.org/r/20200616154311.12314-3-longman@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 5 insertions, 5 deletions

diff --git a/drivers/crypto/marvell/cesa/hash.c b/drivers/crypto/marvell/cesa/hash.c
index bd0bd9ffd6e9..f2a2fc111164 100644
--- a/drivers/crypto/marvell/cesa/hash.c
+++ b/drivers/crypto/marvell/cesa/hash.c
@@ -1157,7 +1157,7 @@ static int mv_cesa_ahmac_pad_init(struct ahash_request *req,
 		}
 
 		/* Set the memory region to 0 to avoid any leak. */
-		kzfree(keydup);
+		kfree_sensitive(keydup);
 
 		if (ret)
 			return ret;
diff --git a/drivers/crypto/marvell/octeontx/otx_cptvf_main.c b/drivers/crypto/marvell/octeontx/otx_cptvf_main.c
index ce3168327a39..228fe8e47e0e 100644
--- a/drivers/crypto/marvell/octeontx/otx_cptvf_main.c
+++ b/drivers/crypto/marvell/octeontx/otx_cptvf_main.c
@@ -68,7 +68,7 @@ static void cleanup_worker_threads(struct otx_cptvf *cptvf)
 	for (i = 0; i < cptvf->num_queues; i++)
 		tasklet_kill(&cwqe_info->vq_wqe[i].twork);
 
-	kzfree(cwqe_info);
+	kfree_sensitive(cwqe_info);
 	cptvf->wqe_info = NULL;
 }
 
@@ -82,7 +82,7 @@ static void free_pending_queues(struct otx_cpt_pending_qinfo *pqinfo)
 			continue;
 
 		/* free single queue */
-		kzfree((queue->head));
+		kfree_sensitive((queue->head));
 		queue->front = 0;
 		queue->rear = 0;
 		queue->qlen = 0;
@@ -176,7 +176,7 @@ static void free_command_queues(struct otx_cptvf *cptvf,
 			chunk->head = NULL;
 			chunk->dma_addr = 0;
 			list_del(&chunk->nextchunk);
-			kzfree(chunk);
+			kfree_sensitive(chunk);
 		}
 		queue->num_chunks = 0;
 		queue->idx = 0;
diff --git a/drivers/crypto/marvell/octeontx/otx_cptvf_reqmgr.h b/drivers/crypto/marvell/octeontx/otx_cptvf_reqmgr.h
index d912fe0c532d..a02d059fb652 100644
--- a/drivers/crypto/marvell/octeontx/otx_cptvf_reqmgr.h
+++ b/drivers/crypto/marvell/octeontx/otx_cptvf_reqmgr.h
@@ -215,7 +215,7 @@ static inline void do_request_cleanup(struct pci_dev *pdev,
 						 DMA_BIDIRECTIONAL);
 		}
 	}
-	kzfree(info);
+	kfree_sensitive(info);
 }
 
 struct otx_cptvf_wqe;