On Tue, Jun 28, 2022 at 10:36:51AM -0300, Jason Gunthorpe wrote: > On Tue, Jun 28, 2022 at 04:21:29AM +0200, Gustavo A. R. Silva wrote: > > > > > Though maybe we could just switch off -Wgnu-variable-sized-type-not-at-end during configuration ? > > > We need to think in a different strategy. > > I think we will need to switch off the warning in userspace - this is > doable for rdma-core. > > On the other hand, if the goal is to enable the array size check > compiler warning I would suggest focusing only on those structs that > actually hit that warning in the kernel. IIRC infiniband doesn't > trigger it because it just pointer casts the flex array to some other > struct. Yep; this is actually why I reverted those changes in rdma (before sending out the patch) when 0-day reported the same problems you pointed out[1]. Also, that's the strategy I'm following right now with the one-element array into flex-array member transformations. I'm addressing those cases in which the trailing array is actually being iterated over, first. I just added the patch to my -next tree, so it can be build-tested by other people, and let's see what else is reported this week. :) -- Gustavo [1] https://lore.kernel.org/lkml/620ca2a5.NkAEIDEfiYoxE9%2Fu%25lkp@xxxxxxxxx/ > > It isn't actually an array it is a placeholder for a trailing > structure, so it is never indexed. > > This is also why we hit the warning because the convient way for > userspace to compose the message is to squash the header and trailer > structs together in a super struct on the stack, then invoke the > ioctl. > > Jason
