Messages in this thread Patch in this message | | | From | Alessandro Astone <> | Subject | [PATCH v2 1/2] binder: Address corner cases in deferred copy and fixup | Date | Fri, 15 Apr 2022 14:00:15 +0200 |
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When handling BINDER_TYPE_FDA object we are pushing a parent fixup with a certain skip_size but no scatter-gather copy object, since the copy is handled standalone. If BINDER_TYPE_FDA is the last children the scatter-gather copy loop will never stop to skip it, thus we are left with an item in the parent fixup list. This will trigger the BUG_ON().
This is reproducible in android when playing a video. We receive a transaction that looks like this: obj[0] BINDER_TYPE_PTR, parent obj[1] BINDER_TYPE_PTR, child obj[2] BINDER_TYPE_PTR, child obj[3] BINDER_TYPE_FDA, child
Fixes: 09184ae9b575 ("binder: defer copies of pre-patched txn data") Signed-off-by: Alessandro Astone <ales.astone@gmail.com> --- drivers/android/binder.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 8351c5638880..31176edb1069 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -2295,6 +2295,7 @@ static int binder_do_deferred_txn_copies(struct binder_alloc *alloc, { int ret = 0; struct binder_sg_copy *sgc, *tmpsgc; + struct binder_ptr_fixup *tmppf; struct binder_ptr_fixup *pf = list_first_entry_or_null(pf_head, struct binder_ptr_fixup, node); @@ -2349,7 +2350,11 @@ static int binder_do_deferred_txn_copies(struct binder_alloc *alloc, list_del(&sgc->node); kfree(sgc); } - BUG_ON(!list_empty(pf_head)); + list_for_each_entry_safe(pf, tmppf, pf_head, node) { + BUG_ON(pf->skip_size == 0); + list_del(&pf->node); + kfree(pf); + } BUG_ON(!list_empty(sgc_head)); return ret > 0 ? -EINVAL : ret; -- 2.35.1
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