From: Waiman Long <[email protected]> commit 8982ae527fbef170ef298650c15d55a9ccd33973 upstream.
The kzfree() function is normally used to clear some sensitive information, like encryption keys, in the buffer before freeing it back to the pool. Memset() is currently used for buffer clearing. However unlikely, there is still a non-zero probability that the compiler may choose to optimize away the memory clearing especially if LTO is being used in the future. To make sure that this optimization will never happen, memzero_explicit(), which is introduced in v3.18, is now used in kzfree() to future-proof it. Link: http://lkml.kernel.org/r/[email protected] Fixes: 3ef0e5ba4673 ("slab: introduce kzfree()") Signed-off-by: Waiman Long <[email protected]> Acked-by: Michal Hocko <[email protected]> Cc: 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: Johannes Weiner <[email protected]> Cc: Dan Carpenter <[email protected]> Cc: "Jason A . Donenfeld" <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- mm/slab_common.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/slab_common.c b/mm/slab_common.c index 39e382acb0b86..b5776b1301f0c 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -1540,7 +1540,7 @@ void kzfree(const void *p) if (unlikely(ZERO_OR_NULL_PTR(mem))) return; ks = ksize(mem); - memset(mem, 0, ks); + memzero_explicit(mem, ks); kfree(mem); } EXPORT_SYMBOL(kzfree); -- 2.25.1
