[PATCH 4.19 79/88] mm: slub: fix conversion of freelist_corrupted()

Greg Kroah-Hartman
2020-09-08T18:05:09Z

From: Eugeniu Rosca <erosca@de.adit-jv.com>

commit dc07a728d49cf025f5da2c31add438d839d076c0 upstream.

Commit 52f23478081ae0 ("mm/slub.c: fix corrupted freechain in
deactivate_slab()") suffered an update when picked up from LKML [1].

Specifically, relocating 'freelist = NULL' into 'freelist_corrupted()'
created a no-op statement. Fix it by sticking to the behavior intended
in the original patch [1]. In addition, make freelist_corrupted()
immune to passing NULL instead of &freelist.

The issue has been spotted via static analysis and code review.

[1] https://lore.kernel.org/linux-mm/20200331031450.12182-1-dongli.zhang@oracle.com/

Fixes: 52f23478081ae0 ("mm/slub.c: fix corrupted freechain in deactivate_slab()")
Signed-off-by: Eugeniu Rosca <erosca@de.adit-jv.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Dongli Zhang <dongli.zhang@oracle.com>
Cc: Joe Jin <joe.jin@oracle.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20200824130643.10291-1-erosca@de.adit-jv.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
mm/slub.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

--- a/mm/slub.c
+++ b/mm/slub.c
@@ -646,12 +646,12 @@ static void slab_fix(struct kmem_cache *
}

static bool freelist_corrupted(struct kmem_cache *s, struct page *page,
- void *freelist, void *nextfree)
+ void **freelist, void *nextfree)
{
if ((s->flags & SLAB_CONSISTENCY_CHECKS) &&
- !check_valid_pointer(s, page, nextfree)) {
- object_err(s, page, freelist, "Freechain corrupt");
- freelist = NULL;
+ !check_valid_pointer(s, page, nextfree) && freelist) {
+ object_err(s, page, *freelist, "Freechain corrupt");
+ *freelist = NULL;
slab_fix(s, "Isolate corrupted freechain");
return true;
}
@@ -1343,7 +1343,7 @@ static inline void dec_slabs_node(struct
int objects) {}

static bool freelist_corrupted(struct kmem_cache *s, struct page *page,
- void *freelist, void *nextfree)
+ void **freelist, void *nextfree)
{
return false;
}
@@ -2037,7 +2037,7 @@ static void deactivate_slab(struct kmem_
* 'freelist' is already corrupted. So isolate all objects
* starting at 'freelist'.
*/
- if (freelist_corrupted(s, page, freelist, nextfree))
+ if (freelist_corrupted(s, page, &freelist, nextfree))
break;

do {