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>

4 files changed, 14 insertions, 14 deletions

diff --git a/drivers/crypto/cavium/cpt/cptvf_main.c b/drivers/crypto/cavium/cpt/cptvf_main.c
index 0f72e9abdefe..a15245992cf9 100644
--- a/drivers/crypto/cavium/cpt/cptvf_main.c
+++ b/drivers/crypto/cavium/cpt/cptvf_main.c
@@ -74,7 +74,7 @@ static void cleanup_worker_threads(struct cpt_vf *cptvf)
 	for (i = 0; i < cptvf->nr_queues; i++)
 		tasklet_kill(&cwqe_info->vq_wqe[i].twork);
 
-	kzfree(cwqe_info);
+	kfree_sensitive(cwqe_info);
 	cptvf->wqe_info = NULL;
 }
 
@@ -88,7 +88,7 @@ static void free_pending_queues(struct pending_qinfo *pqinfo)
 			continue;
 
 		/* free single queue */
-		kzfree((queue->head));
+		kfree_sensitive((queue->head));
 
 		queue->front = 0;
 		queue->rear = 0;
@@ -189,7 +189,7 @@ static void free_command_queues(struct cpt_vf *cptvf,
 			chunk->head = NULL;
 			chunk->dma_addr = 0;
 			hlist_del(&chunk->nextchunk);
-			kzfree(chunk);
+			kfree_sensitive(chunk);
 		}
 
 		queue->nchunks = 0;
diff --git a/drivers/crypto/cavium/cpt/cptvf_reqmanager.c b/drivers/crypto/cavium/cpt/cptvf_reqmanager.c
index 3878b01e19e1..dc5fda522719 100644
--- a/drivers/crypto/cavium/cpt/cptvf_reqmanager.c
+++ b/drivers/crypto/cavium/cpt/cptvf_reqmanager.c
@@ -305,12 +305,12 @@ static void do_request_cleanup(struct cpt_vf *cptvf,
 		}
 	}
 
-	kzfree(info->scatter_components);
-	kzfree(info->gather_components);
-	kzfree(info->out_buffer);
-	kzfree(info->in_buffer);
-	kzfree((void *)info->completion_addr);
-	kzfree(info);
+	kfree_sensitive(info->scatter_components);
+	kfree_sensitive(info->gather_components);
+	kfree_sensitive(info->out_buffer);
+	kfree_sensitive(info->in_buffer);
+	kfree_sensitive((void *)info->completion_addr);
+	kfree_sensitive(info);
 }
 
 static void do_post_process(struct cpt_vf *cptvf, struct cpt_info_buffer *info)
diff --git a/drivers/crypto/cavium/nitrox/nitrox_lib.c b/drivers/crypto/cavium/nitrox/nitrox_lib.c
index 5cbc64b851b9..a5cdc2b48bd6 100644
--- a/drivers/crypto/cavium/nitrox/nitrox_lib.c
+++ b/drivers/crypto/cavium/nitrox/nitrox_lib.c
@@ -90,7 +90,7 @@ static void nitrox_free_aqm_queues(struct nitrox_device *ndev)
 
 	for (i = 0; i < ndev->nr_queues; i++) {
 		nitrox_cmdq_cleanup(ndev->aqmq[i]);
-		kzfree(ndev->aqmq[i]);
+		kfree_sensitive(ndev->aqmq[i]);
 		ndev->aqmq[i] = NULL;
 	}
 }
@@ -122,7 +122,7 @@ static int nitrox_alloc_aqm_queues(struct nitrox_device *ndev)
 
 		err = nitrox_cmdq_init(cmdq, AQM_Q_ALIGN_BYTES);
 		if (err) {
-			kzfree(cmdq);
+			kfree_sensitive(cmdq);
 			goto aqmq_fail;
 		}
 		ndev->aqmq[i] = cmdq;
diff --git a/drivers/crypto/cavium/zip/zip_crypto.c b/drivers/crypto/cavium/zip/zip_crypto.c
index 4985bc812b0e..7df71fcebe8f 100644
--- a/drivers/crypto/cavium/zip/zip_crypto.c
+++ b/drivers/crypto/cavium/zip/zip_crypto.c
@@ -260,7 +260,7 @@ void *zip_alloc_scomp_ctx_deflate(struct crypto_scomp *tfm)
 	ret = zip_ctx_init(zip_ctx, 0);
 
 	if (ret) {
-		kzfree(zip_ctx);
+		kfree_sensitive(zip_ctx);
 		return ERR_PTR(ret);
 	}
 
@@ -279,7 +279,7 @@ void *zip_alloc_scomp_ctx_lzs(struct crypto_scomp *tfm)
 	ret = zip_ctx_init(zip_ctx, 1);
 
 	if (ret) {
-		kzfree(zip_ctx);
+		kfree_sensitive(zip_ctx);
 		return ERR_PTR(ret);
 	}
 
@@ -291,7 +291,7 @@ void zip_free_scomp_ctx(struct crypto_scomp *tfm, void *ctx)
 	struct zip_kernel_ctx *zip_ctx = ctx;
 
 	zip_ctx_exit(zip_ctx);
-	kzfree(zip_ctx);
+	kfree_sensitive(zip_ctx);
 }
 
 int zip_scomp_compress(struct crypto_scomp *tfm,