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| author | Michel Dänzer <michel.daenzer@amd.com> | 2018-07-04 18:14:05 +0300 |
|---|---|---|
| committer | Sumit Semwal <sumit.semwal@linaro.org> | 2018-07-16 17:50:37 +0300 |
| commit | 7f43ef9f0d98abbc0eb5e697628ec06756bf60a9 (patch) | |
| tree | e1427219f16792cbf6d4c0dab26b1255a336e4c2 /drivers/dma-buf/reservation.c | |
| parent | 3273fc63e1ed4866fe10a582f4203f2aa142b216 (diff) | |
| download | linux-7f43ef9f0d98abbc0eb5e697628ec06756bf60a9.tar.xz | |
dma-buf: Move BUG_ON from _add_shared_fence to _add_shared_inplace
Fixes the BUG_ON spuriously triggering under the following
circumstances:
* reservation_object_reserve_shared is called with shared_count ==
shared_max - 1, so obj->staged is freed in preparation of an in-place
update.
* reservation_object_add_shared_fence is called with the first fence,
after which shared_count == shared_max.
* reservation_object_add_shared_fence is called with a follow-up fence
from the same context.
In the second reservation_object_add_shared_fence call, the BUG_ON
triggers. However, nothing bad would happen in
reservation_object_add_shared_inplace, since both fences are from the
same context, so they only occupy a single slot.
Prevent this by moving the BUG_ON to where an overflow would actually
happen (e.g. if a buggy caller didn't call
reservation_object_reserve_shared before).
v2:
* Fix description of breaking scenario (Christian König)
* Add bugzilla reference
Cc: stable@vger.kernel.org
Bugzilla: https://bugs.freedesktop.org/106418
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> # v1
Reviewed-by: Christian König <christian.koenig@amd.com> # v1
Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20180704151405.10357-1-michel@daenzer.net
Diffstat (limited to 'drivers/dma-buf/reservation.c')
| -rw-r--r-- | drivers/dma-buf/reservation.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/dma-buf/reservation.c b/drivers/dma-buf/reservation.c index 20bf90f4ee63..6c95f61a32e7 100644 --- a/drivers/dma-buf/reservation.c +++ b/drivers/dma-buf/reservation.c @@ -141,6 +141,7 @@ reservation_object_add_shared_inplace(struct reservation_object *obj, if (signaled) { RCU_INIT_POINTER(fobj->shared[signaled_idx], fence); } else { + BUG_ON(fobj->shared_count >= fobj->shared_max); RCU_INIT_POINTER(fobj->shared[fobj->shared_count], fence); fobj->shared_count++; } @@ -230,10 +231,9 @@ void reservation_object_add_shared_fence(struct reservation_object *obj, old = reservation_object_get_list(obj); obj->staged = NULL; - if (!fobj) { - BUG_ON(old->shared_count >= old->shared_max); + if (!fobj) reservation_object_add_shared_inplace(obj, old, fence); - } else + else reservation_object_add_shared_replace(obj, old, fobj, fence); } EXPORT_SYMBOL(reservation_object_add_shared_fence); |