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drm/i915: Don't adjust priority on an already signaled fence
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When we retire a signaled fence, we free the dependency tree. However,
we skip clearing the list so that if we then try to adjust the priority
of the signaled fence, we may walk the list of freed dependencies.

[ 3083.156757] ==================================================================
[ 3083.156806] BUG: KASAN: use-after-free in execlists_schedule+0x199/0x660 [i915]
[ 3083.156810] Read of size 8 at addr ffff8806bf20f400 by task Xorg/831

[ 3083.156815] CPU: 0 PID: 831 Comm: Xorg Not tainted 4.15.0-rc6-no-psn+ #1
[ 3083.156817] Hardware name: Notebook                         N24_25BU/N24_25BU, BIOS 5.12 02/17/2017
[ 3083.156818] Call Trace:
[ 3083.156823]  dump_stack+0x5c/0x7a
[ 3083.156827]  print_address_description+0x6b/0x290
[ 3083.156830]  kasan_report+0x28f/0x380
[ 3083.156872]  ? execlists_schedule+0x199/0x660 [i915]
[ 3083.156914]  execlists_schedule+0x199/0x660 [i915]
[ 3083.156956]  ? intel_crtc_atomic_check+0x146/0x4e0 [i915]
[ 3083.156997]  ? execlists_submit_request+0xe0/0xe0 [i915]
[ 3083.157038]  ? i915_vma_misplaced.part.4+0x25/0xb0 [i915]
[ 3083.157079]  ? __i915_vma_do_pin+0x7c8/0xc80 [i915]
[ 3083.157121]  ? intel_atomic_state_alloc+0x44/0x60 [i915]
[ 3083.157130]  ? drm_atomic_helper_page_flip+0x3e/0xb0 [drm_kms_helper]
[ 3083.157145]  ? drm_mode_page_flip_ioctl+0x7d2/0x850 [drm]
[ 3083.157159]  ? drm_ioctl_kernel+0xa7/0xf0 [drm]
[ 3083.157172]  ? drm_ioctl+0x45b/0x560 [drm]
[ 3083.157211]  i915_gem_object_wait_priority+0x14c/0x2c0 [i915]
[ 3083.157251]  ? i915_gem_get_aperture_ioctl+0x150/0x150 [i915]
[ 3083.157290]  ? i915_vma_pin_fence+0x1d8/0x320 [i915]
[ 3083.157331]  ? intel_pin_and_fence_fb_obj+0x175/0x250 [i915]
[ 3083.157372]  ? intel_rotation_info_size+0x60/0x60 [i915]
[ 3083.157413]  ? intel_link_compute_m_n+0x80/0x80 [i915]
[ 3083.157428]  ? drm_dev_printk+0x1b0/0x1b0 [drm]
[ 3083.157443]  ? drm_dev_printk+0x1b0/0x1b0 [drm]
[ 3083.157485]  intel_prepare_plane_fb+0x2f8/0x5a0 [i915]
[ 3083.157527]  ? intel_crtc_get_vblank_counter+0x80/0x80 [i915]
[ 3083.157536]  drm_atomic_helper_prepare_planes+0xa0/0x1c0 [drm_kms_helper]
[ 3083.157587]  intel_atomic_commit+0x12e/0x4e0 [i915]
[ 3083.157605]  drm_atomic_helper_page_flip+0xa2/0xb0 [drm_kms_helper]
[ 3083.157621]  drm_mode_page_flip_ioctl+0x7d2/0x850 [drm]
[ 3083.157638]  ? drm_mode_cursor2_ioctl+0x10/0x10 [drm]
[ 3083.157652]  ? drm_lease_owner+0x1a/0x30 [drm]
[ 3083.157668]  ? drm_mode_cursor2_ioctl+0x10/0x10 [drm]
[ 3083.157681]  drm_ioctl_kernel+0xa7/0xf0 [drm]
[ 3083.157696]  drm_ioctl+0x45b/0x560 [drm]
[ 3083.157711]  ? drm_mode_cursor2_ioctl+0x10/0x10 [drm]
[ 3083.157725]  ? drm_getstats+0x20/0x20 [drm]
[ 3083.157729]  ? timerqueue_del+0x49/0x80
[ 3083.157732]  ? __remove_hrtimer+0x62/0xb0
[ 3083.157735]  ? hrtimer_try_to_cancel+0x173/0x210
[ 3083.157738]  do_vfs_ioctl+0x13b/0x880
[ 3083.157741]  ? ioctl_preallocate+0x140/0x140
[ 3083.157744]  ? _raw_spin_unlock_irq+0xe/0x30
[ 3083.157746]  ? do_setitimer+0x234/0x370
[ 3083.157750]  ? SyS_setitimer+0x19e/0x1b0
[ 3083.157752]  ? SyS_alarm+0x140/0x140
[ 3083.157755]  ? __rcu_read_unlock+0x66/0x80
[ 3083.157757]  ? __fget+0xc4/0x100
[ 3083.157760]  SyS_ioctl+0x74/0x80
[ 3083.157763]  entry_SYSCALL_64_fastpath+0x1a/0x7d
[ 3083.157765] RIP: 0033:0x7f6135d0c6a7
[ 3083.157767] RSP: 002b:00007fff01451888 EFLAGS: 00003246 ORIG_RAX: 0000000000000010
[ 3083.157769] RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007f6135d0c6a7
[ 3083.157771] RDX: 00007fff01451950 RSI: 00000000c01864b0 RDI: 000000000000000c
[ 3083.157772] RBP: 00007f613076f600 R08: 0000000000000001 R09: 0000000000000000
[ 3083.157773] R10: 0000000000000060 R11: 0000000000003246 R12: 0000000000000000
[ 3083.157774] R13: 0000000000000060 R14: 000000000000001b R15: 0000000000000060

[ 3083.157779] Allocated by task 831:
[ 3083.157783]  kmem_cache_alloc+0xc0/0x200
[ 3083.157822]  i915_gem_request_await_dma_fence+0x2c4/0x5d0 [i915]
[ 3083.157861]  i915_gem_request_await_object+0x321/0x370 [i915]
[ 3083.157900]  i915_gem_do_execbuffer+0x1165/0x19c0 [i915]
[ 3083.157937]  i915_gem_execbuffer2+0x1ad/0x550 [i915]
[ 3083.157950]  drm_ioctl_kernel+0xa7/0xf0 [drm]
[ 3083.157962]  drm_ioctl+0x45b/0x560 [drm]
[ 3083.157964]  do_vfs_ioctl+0x13b/0x880
[ 3083.157966]  SyS_ioctl+0x74/0x80
[ 3083.157968]  entry_SYSCALL_64_fastpath+0x1a/0x7d

[ 3083.157971] Freed by task 831:
[ 3083.157973]  kmem_cache_free+0x77/0x220
[ 3083.158012]  i915_gem_request_retire+0x72c/0xa70 [i915]
[ 3083.158051]  i915_gem_request_alloc+0x1e9/0x8b0 [i915]
[ 3083.158089]  i915_gem_do_execbuffer+0xa96/0x19c0 [i915]
[ 3083.158127]  i915_gem_execbuffer2+0x1ad/0x550 [i915]
[ 3083.158140]  drm_ioctl_kernel+0xa7/0xf0 [drm]
[ 3083.158153]  drm_ioctl+0x45b/0x560 [drm]
[ 3083.158155]  do_vfs_ioctl+0x13b/0x880
[ 3083.158156]  SyS_ioctl+0x74/0x80
[ 3083.158158]  entry_SYSCALL_64_fastpath+0x1a/0x7d

[ 3083.158162] The buggy address belongs to the object at ffff8806bf20f400
                which belongs to the cache i915_dependency of size 64
[ 3083.158166] The buggy address is located 0 bytes inside of
                64-byte region [ffff8806bf20f400, ffff8806bf20f440)
[ 3083.158168] The buggy address belongs to the page:
[ 3083.158171] page:00000000d43decc4 count:1 mapcount:0 mapping:          (null) index:0x0
[ 3083.158174] flags: 0x17ffe0000000100(slab)
[ 3083.158179] raw: 017ffe0000000100 0000000000000000 0000000000000000 0000000180200020
[ 3083.158182] raw: ffffea001afc16c0 0000000500000005 ffff880731b881c0 0000000000000000
[ 3083.158184] page dumped because: kasan: bad access detected

[ 3083.158187] Memory state around the buggy address:
[ 3083.158190]  ffff8806bf20f300: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
[ 3083.158192]  ffff8806bf20f380: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
[ 3083.158195] >ffff8806bf20f400: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
[ 3083.158196]                    ^
[ 3083.158199]  ffff8806bf20f480: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
[ 3083.158201]  ffff8806bf20f500: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
[ 3083.158203] ==================================================================

Reported-by: Alexandru Chirvasitu <[email protected]>
Reported-by: Mike Keehan <[email protected]>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=104436
Fixes: 1f18122 ("drm/i915/execlists: Keep request->priority for its lifetime")
Signed-off-by: Chris Wilson <[email protected]>
Cc: Alexandru Chirvasitu <[email protected]>
Cc: Michał Winiarski <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Cc: Tvrtko Ursulin <[email protected]>
Tested-by: Alexandru Chirvasitu <[email protected]>
Reviewed-by: Michał Winiarski <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
(cherry picked from commit c218ee0)
Signed-off-by: Jani Nikula <[email protected]>
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@ickle @jnikula
ickle authored and jnikula committed Jan 11, 2018
1 parent 4636bda commit 5005c85
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Showing 2 changed files with 4 additions and 1 deletion.
2 changes: 1 addition & 1 deletion drivers/gpu/drm/i915/i915_gem.c
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Original file line number Diff line number Diff line change
Expand Up @@ -467,7 +467,7 @@ static void __fence_set_priority(struct dma_fence *fence, int prio)
struct drm_i915_gem_request *rq;
struct intel_engine_cs *engine;

if (!dma_fence_is_i915(fence))
if (dma_fence_is_signaled(fence) || !dma_fence_is_i915(fence))
return;

rq = to_request(fence);
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3 changes: 3 additions & 0 deletions drivers/gpu/drm/i915/intel_lrc.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -974,6 +974,9 @@ static void execlists_schedule(struct drm_i915_gem_request *request, int prio)

GEM_BUG_ON(prio == I915_PRIORITY_INVALID);

if (i915_gem_request_completed(request))
return;

if (prio <= READ_ONCE(request->priotree.priority))
return;

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