From 62f8c07d84064940020c7b8a41cc8d26b68e8262 Mon Sep 17 00:00:00 2001 From: Alessandro Astone Date: Fri, 15 Apr 2022 14:00:15 +0200 Subject: [PATCH] binder: Address corner cases in deferred copy and fixup commit 2d1746e3fda0c3612143d7c06f8e1d1830c13e23 upstream. 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") Acked-by: Todd Kjos Cc: stable Signed-off-by: Alessandro Astone Link: https://lore.kernel.org/r/20220415120015.52684-2-ales.astone@gmail.com Signed-off-by: Greg Kroah-Hartman --- 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 7017102a3a5f..f3b639e89dd8 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;