Kasan spotted
[IGT] gem_tiled_pread_pwrite: exiting, ret=0
==================================================================
BUG: KASAN: use-after-free in __i915_gem_object_reset_page_iter+0x15c/0x170 [i915]
Read of size 8 at addr ffff8801359da310 by task kworker/3:2/182
CPU: 3 PID: 182 Comm: kworker/3:2 Tainted: G U 4.14.0-rc6-CI-Custom_3340+ #1
Hardware name: Intel Corp. Geminilake/GLK RVP1 DDR4 (05), BIOS GELKRVPA.X64.0062.B30.1708222146 08/22/2017
Workqueue: events __i915_gem_free_work [i915]
Call Trace:
dump_stack+0x68/0xa0
print_address_description+0x78/0x290
? __i915_gem_object_reset_page_iter+0x15c/0x170 [i915]
kasan_report+0x23d/0x350
__asan_report_load8_noabort+0x19/0x20
__i915_gem_object_reset_page_iter+0x15c/0x170 [i915]
? i915_gem_object_truncate+0x100/0x100 [i915]
? lock_acquire+0x380/0x380
__i915_gem_object_put_pages+0x30d/0x530 [i915]
__i915_gem_free_objects+0x551/0xbd0 [i915]
? lock_acquire+0x13e/0x380
__i915_gem_free_work+0x4e/0x70 [i915]
process_one_work+0x6f6/0x1590
? pwq_dec_nr_in_flight+0x2b0/0x2b0
worker_thread+0xe6/0xe90
? pci_mmcfg_check_reserved+0x110/0x110
kthread+0x309/0x410
? process_one_work+0x1590/0x1590
? kthread_create_on_node+0xb0/0xb0
ret_from_fork+0x27/0x40
Allocated by task 1801:
save_stack_trace+0x1b/0x20
kasan_kmalloc+0xee/0x190
kasan_slab_alloc+0x12/0x20
kmem_cache_alloc+0xdc/0x2e0
radix_tree_node_alloc.constprop.12+0x48/0x330
__radix_tree_create+0x274/0x480
__radix_tree_insert+0xa2/0x610
i915_gem_object_get_sg+0x224/0x670 [i915]
i915_gem_object_get_page+0xb5/0x1c0 [i915]
i915_gem_pread_ioctl+0x822/0xf60 [i915]
drm_ioctl_kernel+0x13f/0x1c0
drm_ioctl+0x6cf/0x980
do_vfs_ioctl+0x184/0xf30
SyS_ioctl+0x41/0x70
entry_SYSCALL_64_fastpath+0x1c/0xb1
Freed by task 37:
save_stack_trace+0x1b/0x20
kasan_slab_free+0xaf/0x190
kmem_cache_free+0xbf/0x340
radix_tree_node_rcu_free+0x79/0x90
rcu_process_callbacks+0x46d/0xf40
__do_softirq+0x21c/0x8d3
The buggy address belongs to the object at ffff8801359da0f0
which belongs to the cache radix_tree_node of size 576
The buggy address is located 544 bytes inside of
576-byte region [ffff8801359da0f0, ffff8801359da330)
The buggy address belongs to the page:
page:ffffea0004d67600 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0
flags: 0x8000000000008100(slab|head)
raw: 8000000000008100 0000000000000000 0000000000000000 0000000100110011
raw: ffffea0004b52920 ffffea0004b38020 ffff88015b416a80 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff8801359da200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8801359da280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8801359da300: fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc
^
ffff8801359da380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8801359da400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
Disabling lock debugging due to kernel taint
which looks like the slab containing the radixtree iter was freed as we
traversed the tree, taking the rcu read lock across the loop should
prevent that (deferring all the frees until the end).
Reported-by: Tomi Sarvela <tomi.p.sarvela@xxxxxxxxx>
Fixes: 96d776345277 ("drm/i915: Use a radixtree for random access to the object's backing storage")
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_gem.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index d803ef5f4a7f..9d9c37ff51c9 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2267,8 +2267,10 @@ static void __i915_gem_object_reset_page_iter(struct drm_i915_gem_object *obj)
struct radix_tree_iter iter;
void __rcu **slot;
+ rcu_read_lock();
radix_tree_for_each_slot(slot, &obj->mm.get_page.radix, &iter, 0)
radix_tree_delete(&obj->mm.get_page.radix, iter.index);
+ rcu_read_unlock();
}
void __i915_gem_object_put_pages(struct drm_i915_gem_object *obj,
--
2.15.0.rc2
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