The patch titled
Subject: mm: ksize() should silently accept a NULL pointer
has been added to the -mm tree. Its filename is
mm-ksize-should-silently-accept-a-null-pointer.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-ksize-should-silently-accept-a-null-pointer.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-ksize-should-silently-accept-a-null-pointer.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: William Kucharski <william.kucharski@xxxxxxxxxx>
Subject: mm: ksize() should silently accept a NULL pointer
Other mm routines such as kfree() and kzfree() silently do the right thing
if passed a NULL pointer, so ksize() should do the same.
Link: http://lkml.kernel.org/r/20200616225409.4670-1-william.kucharski@xxxxxxxxxx
Signed-off-by: William Kucharski <william.kucharski@xxxxxxxxxx>
Reviewed-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/slab_common.c | 14 +++++---------
1 file changed, 5 insertions(+), 9 deletions(-)
--- a/mm/slab_common.c~mm-ksize-should-silently-accept-a-null-pointer
+++ a/mm/slab_common.c
@@ -1660,10 +1660,9 @@ static __always_inline void *__do_kreall
gfp_t flags)
{
void *ret;
- size_t ks = 0;
+ size_t ks;
- if (p)
- ks = ksize(p);
+ ks = ksize(p);
if (ks >= new_size) {
p = kasan_krealloc((void *)p, new_size, flags);
@@ -1723,10 +1722,9 @@ void kfree_sensitive(const void *p)
size_t ks;
void *mem = (void *)p;
- if (unlikely(ZERO_OR_NULL_PTR(mem)))
- return;
ks = ksize(mem);
- memzero_explicit(mem, ks);
+ if (ks)
+ memzero_explicit(mem, ks);
kfree(mem);
}
EXPORT_SYMBOL(kfree_sensitive);
@@ -1749,8 +1747,6 @@ size_t ksize(const void *objp)
{
size_t size;
- if (WARN_ON_ONCE(!objp))
- return 0;
/*
* We need to check that the pointed to object is valid, and only then
* unpoison the shadow memory below. We use __kasan_check_read(), to
@@ -1764,7 +1760,7 @@ size_t ksize(const void *objp)
* We want to perform the check before __ksize(), to avoid potentially
* crashing in __ksize() due to accessing invalid metadata.
*/
- if (unlikely(objp == ZERO_SIZE_PTR) || !__kasan_check_read(objp, 1))
+ if (unlikely(ZERO_OR_NULL_PTR(objp)) || !__kasan_check_read(objp, 1))
return 0;
size = __ksize(objp);
_
Patches currently in -mm which might be from william.kucharski@xxxxxxxxxx are
mm-ksize-should-silently-accept-a-null-pointer.patch
