mm: slub: really fix slab walking for init_on_free
Commit 1b7e816fc80e ("mm: slub: Fix slab walking for init_on_free")
fixed one problem with the slab walking but missed a key detail: When
walking the list, the head and tail pointers need to be updated since we
end up reversing the list as a result. Without doing this, bulk free is
broken.
One way this is exposed is a NULL pointer with slub_debug=F:
=============================================================================
BUG skbuff_head_cache (Tainted: G T): Object already free
-----------------------------------------------------------------------------
INFO: Slab 0x000000000d2d2f8f objects=16 used=3 fp=0x0000000064309071 flags=0x3fff00000000201
BUG: kernel NULL pointer dereference, address: 0000000000000000
Oops: 0000 [#1] PREEMPT SMP PTI
RIP: 0010:print_trailer+0x70/0x1d5
Call Trace:
<IRQ>
free_debug_processing.cold.37+0xc9/0x149
__slab_free+0x22a/0x3d0
kmem_cache_free_bulk+0x415/0x420
__kfree_skb_flush+0x30/0x40
net_rx_action+0x2dd/0x480
__do_softirq+0xf0/0x246
irq_exit+0x93/0xb0
do_IRQ+0xa0/0x110
common_interrupt+0xf/0xf
</IRQ>
Given we're now almost identical to the existing debugging code which
correctly walks the list, combine with that.
Link: https://lkml.kernel.org/r/20191104170303.GA50361@gandi.net
Link: http://lkml.kernel.org/r/20191106222208.26815-1-labbott@redhat.com
Fixes: 1b7e816fc80e ("mm: slub: Fix slab walking for init_on_free")
Signed-off-by: Laura Abbott <labbott at redhat.com>
Reported-by: Thibaut Sautereau <thibaut.sautereau at clip-os.org>
Acked-by: David Rientjes <rientjes at google.com>
Tested-by: Alexander Potapenko <glider at google.com>
Acked-by: Alexander Potapenko <glider at google.com>
Cc: Kees Cook <keescook at chromium.org>
Cc: "David S. Miller" <davem at davemloft.net>
Cc: Vlastimil Babka <vbabka at suse.cz>
Cc: <clipos at ssi.gouv.fr>
Cc: Christoph Lameter <cl at linux.com>
Cc: Pekka Enberg <penberg at kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim at lge.com>
Cc: <stable at vger.kernel.org>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
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