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Commit 4e682ce5 authored by Alessandro Astone's avatar Alessandro Astone Committed by Greg Kroah-Hartman
Browse files

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: default avatarTodd Kjos <tkjos@google.com>
Cc: stable <stable@kernel.org>
Signed-off-by: default avatarAlessandro Astone <ales.astone@gmail.com>
Link: https://lore.kernel.org/r/20220415120015.52684-2-ales.astone@gmail.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarCarlos Llamas <cmllamas@google.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 15e098ab

drivers/android/binder.c

+6 −1
Original line number Diff line number Diff line
@@ -2698,6 +2698,7 @@ 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);
@@ -2752,7 +2753,11 @@ 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;