On Fri, Nov 03, 2023 at 06:24:09AM +1000, David Airlie wrote: > On Fri, Nov 3, 2023 at 6:14 AM Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote: > > > > On Thu, Nov 02, 2023 at 08:21:35PM +0100, Philipp Stanner wrote: > > > The functions (v)memdup_user() are utilized to copy userspace arrays. > > > This is done without overflow checks. > > > > > > Use the new wrappers memdup_array_user() and vmemdup_array_user() to > > > copy the arrays more safely. > > > > > @@ -644,7 +644,7 @@ int con_set_unimap(struct vc_data *vc, ushort ct, struct unipair __user *list) > > > if (!ct) > > > return 0; > > > > > - unilist = vmemdup_user(list, array_size(sizeof(*unilist), ct)); > > > + unilist = vmemdup_array_user(list, ct, sizeof(*unilist)); > > > if (IS_ERR(unilist)) > > > return PTR_ERR(unilist); > > > > a 16bit value times sizeof(something). > > So since it's already using array_size here, moving it to a new helper > for consistency just makes things clearer, and so you are fine with > the patch? Sigh... OK, if you want it spelled out, there we go. I have no objections to the contents of patches; e.g. in case of ppp ioctl it saves the reader a grep in search of structure definitions, which is a good thing. The one and only suggestion I have for those patches is that such patches might be better off with explicit "in this case the overflow is avoided due to <reasons>, but use of this helper makes it obviously safe" - or, in case of real bugs, "the overflow is, indeed, possible here", in which case Fixes: ... and Cc: stable might be in order.
