From d4eaa2837851db2bfed572898bfc17f9a9f9151e Mon Sep 17 00:00:00 2001 From: Waiman Long Date: Thu, 4 Jun 2020 16:48:21 -0700 Subject: 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 Signed-off-by: Waiman Long Signed-off-by: Andrew Morton Reviewed-by: Eric Biggers Acked-by: David Howells Cc: Jarkko Sakkinen Cc: James Morris Cc: "Serge E. Hallyn" Cc: Joe Perches Cc: Matthew Wilcox Cc: David Rientjes Cc: Uladzislau Rezki Link: http://lkml.kernel.org/r/20200407200318.11711-1-longman@redhat.com Signed-off-by: Linus Torvalds --- include/linux/mm.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux') diff --git a/include/linux/mm.h b/include/linux/mm.h index e220ce5185ad..5bfc36320e3c 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -776,6 +776,7 @@ static inline void *kvcalloc(size_t n, size_t size, gfp_t flags) } extern void kvfree(const void *addr); +extern void kvfree_sensitive(const void *addr, size_t len); /* * Mapcount of compound page as a whole, does not include mapped sub-pages. -- cgit v1.2.3-71-gd317