Re: [PATCH] security: keys: Use kvfree_sensitive in a few places

[Alex Dewar]

On 2020-09-11 17:05, Denis Efremov wrote:

Hi,

same patch

https://lkml.org/lkml/2020/8/27/168

Thanks,
Denis

Ah ok. Sorry for the noise!

On 9/11/20 2:44 PM, Alex Dewar wrote:

In big_key.c, there are a few places where memzero_explicit + kvfree is
used. It is better to use kvfree_sensitive instead, which is more
readable and also prevents the compiler from eliding the call to
memzero_explicit. Fix this.

Signed-off-by: Alex Dewar <alex.dewa...@gmail.com>
---
  security/keys/big_key.c | 9 +++------
  1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/security/keys/big_key.c b/security/keys/big_key.c
index 691347dea3c1..d17e5f09eeb8 100644
--- a/security/keys/big_key.c
+++ b/security/keys/big_key.c
@@ -121,8 +121,7 @@ int big_key_preparse(struct key_preparsed_payload *prep)
                *path = file->f_path;
                path_get(path);
                fput(file);
-               memzero_explicit(buf, enclen);
-               kvfree(buf);
+               kvfree_sensitive(buf, enclen);
        } else {
                /* Just store the data in a buffer */
                void *data = kmalloc(datalen, GFP_KERNEL);
@@ -140,8 +139,7 @@ int big_key_preparse(struct key_preparsed_payload *prep)
  err_enckey:
        kfree_sensitive(enckey);
  error:
-       memzero_explicit(buf, enclen);
-       kvfree(buf);
+       kvfree_sensitive(buf, enclen);
        return ret;
  }

@@ -273,8 +271,7 @@ long big_key_read(const struct key *key, char *buffer, size_t buflen)

  err_fput:
                fput(file);
  error:
-               memzero_explicit(buf, enclen);
-               kvfree(buf);
+               kvfree_sensitive(buf, enclen);
        } else {
                ret = datalen;
                memcpy(buffer, key->payload.data[big_key_data], datalen);