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. The change does not affect existing 32bit ABI. Signed-off-by: Serban Constantinescu <[email protected]> --- 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)); 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)); 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))); 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))); 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)); if (put_user(cmd, (uint32_t __user *)ptr)) return -EFAULT; -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
