From: Qian Cai cai@lca.pw
[ Upstream commit 1a62b18d51e5c5ecc0345c85bb9fef870ab721ed ]
Commit 51dedad06b5f ("kasan, slab: make freelist stored without tags") calls kasan_reset_tag() for off-slab slab management object leading to freelist being stored non-tagged.
However, cache_grow_begin() calls alloc_slabmgmt() which calls kmem_cache_alloc_node() assigns a tag for the address and stores it in the shadow address. As the result, it causes endless errors below during boot due to drain_freelist() -> slab_destroy() -> kasan_slab_free() which compares already untagged freelist against the stored tag in the shadow address.
Since off-slab slab management object freelist is such a special case, just store it tagged. Non-off-slab management object freelist is still stored untagged which has not been assigned a tag and should not cause any other troubles with this inconsistency.
BUG: KASAN: double-free or invalid-free in slab_destroy+0x84/0x88 Pointer tag: [ff], memory tag: [99]
CPU: 0 PID: 1376 Comm: kworker/0:4 Tainted: G W 5.1.0-rc3+ #8 Hardware name: HPE Apollo 70 /C01_APACHE_MB , BIOS L50_5.13_1.0.6 07/10/2018 Workqueue: cgroup_destroy css_killed_work_fn Call trace: print_address_description+0x74/0x2a4 kasan_report_invalid_free+0x80/0xc0 __kasan_slab_free+0x204/0x208 kasan_slab_free+0xc/0x18 kmem_cache_free+0xe4/0x254 slab_destroy+0x84/0x88 drain_freelist+0xd0/0x104 __kmem_cache_shrink+0x1ac/0x224 __kmemcg_cache_deactivate+0x1c/0x28 memcg_deactivate_kmem_caches+0xa0/0xe8 memcg_offline_kmem+0x8c/0x3d4 mem_cgroup_css_offline+0x24c/0x290 css_killed_work_fn+0x154/0x618 process_one_work+0x9cc/0x183c worker_thread+0x9b0/0xe38 kthread+0x374/0x390 ret_from_fork+0x10/0x18
Allocated by task 1625: __kasan_kmalloc+0x168/0x240 kasan_slab_alloc+0x18/0x20 kmem_cache_alloc_node+0x1f8/0x3a0 cache_grow_begin+0x4fc/0xa24 cache_alloc_refill+0x2f8/0x3e8 kmem_cache_alloc+0x1bc/0x3bc sock_alloc_inode+0x58/0x334 alloc_inode+0xb8/0x164 new_inode_pseudo+0x20/0xec sock_alloc+0x74/0x284 __sock_create+0xb0/0x58c sock_create+0x98/0xb8 __sys_socket+0x60/0x138 __arm64_sys_socket+0xa4/0x110 el0_svc_handler+0x2c0/0x47c el0_svc+0x8/0xc
Freed by task 1625: __kasan_slab_free+0x114/0x208 kasan_slab_free+0xc/0x18 kfree+0x1a8/0x1e0 single_release+0x7c/0x9c close_pdeo+0x13c/0x43c proc_reg_release+0xec/0x108 __fput+0x2f8/0x784 ____fput+0x1c/0x28 task_work_run+0xc0/0x1b0 do_notify_resume+0xb44/0x1278 work_pending+0x8/0x10
The buggy address belongs to the object at ffff809681b89e00 which belongs to the cache kmalloc-128 of size 128 The buggy address is located 0 bytes inside of 128-byte region [ffff809681b89e00, ffff809681b89e80) The buggy address belongs to the page: page:ffff7fe025a06e00 count:1 mapcount:0 mapping:01ff80082000fb00 index:0xffff809681b8fe04 flags: 0x17ffffffc000200(slab) raw: 017ffffffc000200 ffff7fe025a06d08 ffff7fe022ef7b88 01ff80082000fb00 raw: ffff809681b8fe04 ffff809681b80000 00000001000000e0 0000000000000000 page dumped because: kasan: bad access detected page allocated via order 0, migratetype Unmovable, gfp_mask 0x2420c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_COMP|__GFP_THISNODE) prep_new_page+0x4e0/0x5e0 get_page_from_freelist+0x4ce8/0x50d4 __alloc_pages_nodemask+0x738/0x38b8 cache_grow_begin+0xd8/0xa24 ____cache_alloc_node+0x14c/0x268 __kmalloc+0x1c8/0x3fc ftrace_free_mem+0x408/0x1284 ftrace_free_init_mem+0x20/0x28 kernel_init+0x24/0x548 ret_from_fork+0x10/0x18
Memory state around the buggy address: ffff809681b89c00: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe ffff809681b89d00: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
ffff809681b89e00: 99 99 99 99 99 99 99 99 fe fe fe fe fe fe fe fe
^ ffff809681b89f00: 43 43 43 43 43 fe fe fe fe fe fe fe fe fe fe fe ffff809681b8a000: 6d fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
Link: http://lkml.kernel.org/r/20190403022858.97584-1-cai@lca.pw Fixes: 51dedad06b5f ("kasan, slab: make freelist stored without tags") Signed-off-by: Qian Cai cai@lca.pw Reviewed-by: Andrey Konovalov andreyknvl@google.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: Andrey Ryabinin aryabinin@virtuozzo.com Cc: Alexander Potapenko glider@google.com Cc: Dmitry Vyukov dvyukov@google.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- mm/slab.c | 1 - 1 file changed, 1 deletion(-)
diff --git a/mm/slab.c b/mm/slab.c index 2f2aa8eaf7d9..516df2d854ef 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -2371,7 +2371,6 @@ static void *alloc_slabmgmt(struct kmem_cache *cachep, /* Slab management obj is off-slab. */ freelist = kmem_cache_alloc_node(cachep->freelist_cache, local_flags, nodeid); - freelist = kasan_reset_tag(freelist); if (!freelist) return NULL; } else {