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binder: Address corner cases in deferred copy and fixup 

commit 2d1746e3fd 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: 09184ae9b5 ("binder: defer copies of pre-patched txn data")
Acked-by: Todd Kjos <tkjos@google.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Alessandro Astone <ales.astone@gmail.com>
Link: https://lore.kernel.org/r/20220415120015.52684-2-ales.astone@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alessandro Astone 2022-04-15 14:00:15 +02:00 committed by Greg Kroah-Hartman
parent 3bf989a7be
commit 62f8c07d84
1 changed files with 6 additions and 1 deletions
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7
drivers/android/binder.c
View File

@ -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;