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SubjectRe: [PATCH 1/3] binder: avoid potential data leakage when copying txn
On Tue, Nov 23, 2021 at 11:17:35AM -0800, Todd Kjos wrote:
> Transactions are copied from the sender to the target
> first and objects like BINDER_TYPE_PTR and BINDER_TYPE_FDA
> are then fixed up. This means there is a short period where
> the sender's version of these objects are visible to the
> target prior to the fixups.
>
> Instead of copying all of the data first, copy data only
> after any needed fixups have been applied.
>

This patch needs a fixes tag.

So this patch basically fixes the simple part of the info leak and
patch 3 fixes the complicated part. Have I understood that correctly?

> @@ -2956,7 +2984,11 @@ static void binder_transaction(struct binder_proc *proc,
> }
> ret = binder_translate_fd_array(fda, parent, t, thread,
> in_reply_to);
> - if (ret < 0) {
> + if (ret < 0 ||
> + binder_alloc_copy_to_buffer(&target_proc->alloc,
> + t->buffer,
> + object_offset,
> + fda, sizeof(*fda))) {
> return_error = BR_FAILED_REPLY;
> return_error_param = ret;

"ret" is not a negative error code if binder_translate_fd_array()
succeeds but binder_alloc_copy_to_buffer() fails.


> return_error_line = __LINE__;
> @@ -3028,6 +3060,19 @@ static void binder_transaction(struct binder_proc *proc,
> goto err_bad_object_type;
> }
> }

regards,
dan carpenter

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