mm: add kvfree_sensitive() for freeing sensitive data objects

For kvmalloc'ed data object that contains sensitive information like
cryptographic keys, we need to make sure that the buffer is always cleared
before freeing it.  Using memset() alone for buffer clearing may not
provide certainty as the compiler may compile it away.  To be sure, the
special memzero_explicit() has to be used.

This patch introduces a new kvfree_sensitive() for freeing those sensitive
data objects allocated by kvmalloc().  The relevant places where
kvfree_sensitive() can be used are modified to use it.

Fixes: 4f0882491a14 ("KEYS: Avoid false positive ENOMEM error on key read")
Suggested-by: Linus Torvalds <[email protected]>
Signed-off-by: Waiman Long <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Reviewed-by: Eric Biggers <[email protected]>
Acked-by: David Howells <[email protected]>
Cc: Jarkko Sakkinen <[email protected]>
Cc: James Morris <[email protected]>
Cc: "Serge E. Hallyn" <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Uladzislau Rezki <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions