This is a note to let you know that I've just added the patch titled binder: Address corner cases in deferred copy and fixup to the 5.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: binder-address-corner-cases-in-deferred-copy-and-fixup.patch and it can be found in the queue-5.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Wed Nov 30 01:41:25 PM CET 2022 From: Carlos Llamas <cmllamas@xxxxxxxxxx> Date: Wed, 30 Nov 2022 03:58:04 +0000 Subject: binder: Address corner cases in deferred copy and fixup To: stable@xxxxxxxxxx, "Greg Kroah-Hartman" <gregkh@xxxxxxxxxxxxxxxxxxx>, "Arve Hjønnevåg" <arve@xxxxxxxxxxx>, "Todd Kjos" <tkjos@xxxxxxxxxxx>, "Martijn Coenen" <maco@xxxxxxxxxxx>, "Joel Fernandes" <joel@xxxxxxxxxxxxxxxxx>, "Christian Brauner" <christian@xxxxxxxxxx>, "Hridya Valsaraju" <hridya@xxxxxxxxxx>, "Suren Baghdasaryan" <surenb@xxxxxxxxxx> Cc: linux-kernel@xxxxxxxxxxxxxxx, kernel-team@xxxxxxxxxxx, Alessandro Astone <ales.astone@xxxxxxxxx>, Todd Kjos <tkjos@xxxxxxxxxx>, Carlos Llamas <cmllamas@xxxxxxxxxx> Message-ID: <20221130035805.1823970-6-cmllamas@xxxxxxxxxx> From: Alessandro Astone <ales.astone@xxxxxxxxx> 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 <tkjos@xxxxxxxxxx> Cc: stable <stable@xxxxxxxxxx> Signed-off-by: Alessandro Astone <ales.astone@xxxxxxxxx> Link: https://lore.kernel.org/r/20220415120015.52684-2-ales.astone@xxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Carlos Llamas <cmllamas@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/android/binder.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -2695,6 +2695,7 @@ static int binder_do_deferred_txn_copies { 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); @@ -2749,7 +2750,11 @@ static int binder_do_deferred_txn_copies 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; Patches currently in stable-queue which might be from cmllamas@xxxxxxxxxx are queue-5.10/binder-address-corner-cases-in-deferred-copy-and-fixup.patch queue-5.10/binder-gracefully-handle-binder_type_fda-objects-with-num_fds-0.patch queue-5.10/binder-read-pre-translated-fds-from-sender-buffer.patch queue-5.10/binder-avoid-potential-data-leakage-when-copying-txn.patch queue-5.10/binder-fix-pointer-cast-warning.patch queue-5.10/binder-defer-copies-of-pre-patched-txn-data.patch