From: Eugeniu Rosca <ero...@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.zh...@oracle.com/ Fixes: 52f23478081ae0 ("mm/slub.c: fix corrupted freechain in deactivate_slab()") Signed-off-by: Eugeniu Rosca <ero...@de.adit-jv.com> Signed-off-by: Andrew Morton <a...@linux-foundation.org> Cc: Dongli Zhang <dongli.zh...@oracle.com> Cc: Joe Jin <joe....@oracle.com> Cc: Christoph Lameter <c...@linux.com> Cc: Pekka Enberg <penb...@kernel.org> Cc: David Rientjes <rient...@google.com> Cc: Joonsoo Kim <iamjoonsoo....@lge.com> Cc: <sta...@vger.kernel.org> Link: https://lkml.kernel.org/r/20200824130643.10291-1-ero...@de.adit-jv.com Signed-off-by: Linus Torvalds <torva...@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- mm/slub.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) --- a/mm/slub.c +++ b/mm/slub.c @@ -645,12 +645,12 @@ 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; } @@ -1394,7 +1394,7 @@ 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; } @@ -2086,7 +2086,7 @@ 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 {