Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757691Ab3EaXSP (ORCPT ); Fri, 31 May 2013 19:18:15 -0400 Received: from mail-pd0-f171.google.com ([209.85.192.171]:59493 "EHLO mail-pd0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756951Ab3EaXSI convert rfc822-to-8bit (ORCPT ); Fri, 31 May 2013 19:18:08 -0400 MIME-Version: 1.0 In-Reply-To: <1369217581-16285-6-git-send-email-serban.constantinescu@arm.com> References: <1369217581-16285-1-git-send-email-serban.constantinescu@arm.com> <1369217581-16285-6-git-send-email-serban.constantinescu@arm.com> Date: Fri, 31 May 2013 16:18:08 -0700 Message-ID: Subject: Re: [PATCH v4 5/6] staging: android: binder: fix alignment issues From: =?ISO-8859-1?Q?Arve_Hj=F8nnev=E5g?= To: Serban Constantinescu Cc: LKML , Greg KH , Android Kernel Team , John Stultz , Dave Butcher Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5740 Lines: 133 On Wed, May 22, 2013 at 3:13 AM, Serban Constantinescu wrote: > The Android userspace aligns the data written to the binder buffers to > 4bytes. Thus for 32bit platforms or 64bit platforms running an 32bit > Android userspace we can have a buffer looking like this: > > platform buffer(binder_cmd pointer) size > 32/32 32b 32b 8B > 64/32 32b 64b 12B > 64/64 32b 64b 12B > > Thus the kernel needs to check that the buffer size is aligned to 4bytes > not to (void *) that will be 8bytes on 64bit machines. > > The patch also fixes the alignment issues for the offsets buffer, where > on 64bit systems, if the data_size is not aligned to 8bytes the offset's > start address will be incorrectly calculated. I think this refers to a problem introduced in a previous version of this patch, not a problem with the existing code. If you want to include this in the change description you should make that more clear. > > The change does not affect existing 32bit ABI. > > Signed-off-by: Serban Constantinescu > --- > drivers/staging/android/binder.c | 18 +++++++++--------- > 1 file changed, 9 insertions(+), 9 deletions(-) > > diff --git a/drivers/staging/android/binder.c b/drivers/staging/android/binder.c > index ca79084..72f5bb9 100644 > --- a/drivers/staging/android/binder.c > +++ b/drivers/staging/android/binder.c > @@ -658,8 +658,8 @@ static struct binder_buffer *binder_alloc_buf(struct binder_proc *proc, > return NULL; > } > > - size = ALIGN(data_size, sizeof(void *)) + > - ALIGN(offsets_size, sizeof(void *)); > + size = ALIGN(data_size, sizeof(u32)) + > + ALIGN(offsets_size, sizeof(u32)); I still disagree with this change. There is no reason to not keep the kernel allocated buffers aligned to the native pointer size. The binder_buffer struct contain several pointers that are not longer aligned with this change. > > if (size < data_size || size < offsets_size) { > binder_user_error("%d: got transaction with invalid size %zd-%zd\n", > @@ -807,8 +807,8 @@ static void binder_free_buf(struct binder_proc *proc, > > buffer_size = binder_buffer_size(proc, buffer); > > - size = ALIGN(buffer->data_size, sizeof(void *)) + > - ALIGN(buffer->offsets_size, sizeof(void *)); > + size = ALIGN(buffer->data_size, sizeof(u32)) + > + ALIGN(buffer->offsets_size, sizeof(u32)); This change should also be removed. > > binder_debug(BINDER_DEBUG_BUFFER_ALLOC, > "%d: binder_free_buf %p size %zd buffer_size %zd\n", > @@ -1238,7 +1238,7 @@ static void binder_transaction_buffer_release(struct binder_proc *proc, > if (buffer->target_node) > binder_dec_node(buffer->target_node, 1, 0); > > - offp = (size_t *)(buffer->data + ALIGN(buffer->data_size, sizeof(void *))); > + offp = (size_t *)(buffer->data + ALIGN(buffer->data_size, sizeof(u32))); This change should also be removed. > if (failed_at) > off_end = failed_at; > else > @@ -1247,7 +1247,7 @@ static void binder_transaction_buffer_release(struct binder_proc *proc, > struct flat_binder_object *fp; > if (*offp > buffer->data_size - sizeof(*fp) || > buffer->data_size < sizeof(*fp) || > - !IS_ALIGNED(*offp, sizeof(void *))) { > + !IS_ALIGNED(*offp, sizeof(u32))) { > pr_err("transaction release %d bad offset %zd, size %zd\n", > debug_id, *offp, buffer->data_size); > continue; > @@ -1471,7 +1471,7 @@ static void binder_transaction(struct binder_proc *proc, > if (target_node) > binder_inc_node(target_node, 1, 0, NULL); > > - offp = (size_t *)(t->buffer->data + ALIGN(tr->data_size, sizeof(void *))); > + offp = (size_t *)(t->buffer->data + ALIGN(tr->data_size, sizeof(u32))); This change should also be removed. > > if (copy_from_user(t->buffer->data, tr->data.ptr.buffer, tr->data_size)) { > binder_user_error("%d:%d got transaction with invalid data ptr\n", > @@ -1496,7 +1496,7 @@ static void binder_transaction(struct binder_proc *proc, > struct flat_binder_object *fp; > if (*offp > t->buffer->data_size - sizeof(*fp) || > t->buffer->data_size < sizeof(*fp) || > - !IS_ALIGNED(*offp, sizeof(void *))) { > + !IS_ALIGNED(*offp, sizeof(u32))) { > binder_user_error("%d:%d got transaction with invalid offset, %zd\n", > proc->pid, thread->pid, *offp); > return_error = BR_FAILED_REPLY; > @@ -2332,7 +2332,7 @@ retry: > proc->user_buffer_offset; > tr.data.ptr.offsets = tr.data.ptr.buffer + > ALIGN(t->buffer->data_size, > - sizeof(void *)); > + sizeof(u32)); This change should also be removed. > > if (put_user(cmd, (uint32_t __user *)ptr)) > return -EFAULT; > -- > 1.7.9.5 > -- Arve Hj?nnev?g -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/