Re: [PATCH] keys/encrypted: Fix two crypto-on-the-stack bugs

On Tue, Dec 13, 2016 at 08:40:00AM -0800, Andy Lutomirski wrote: > But I think this is rather silly. Joerg, Linus, etc: would it be okay > to change lib/dma-debug.c to allow DMA *from* rodata? Yeah, this would be fine for DMA_TO_DEVICE mappings. At least I can't think of a reason right now to

Re: [PATCH] keys/encrypted: Fix two crypto-on-the-stack bugs

Andy Lutomirski wrote: > I don't know whether you're right, but that sounds a bit silly to me. > This is a *tiny* amount of memory. Assuming a 1MiB kernel image in 4K pages, that gets you back a couple of pages I think - useful if you've only got a few MiB of RAM. David --

Re: [PATCH] keys/encrypted: Fix two crypto-on-the-stack bugs

Andy Lutomirski wrote: > After all, rodata is ordinary memory, is backed by struct page, etc. Is that actually true? I thought some arches excluded the kernel image from the page struct array to make the array consume less memory. David -- To unsubscribe from this list:

Re: [PATCH] keys/encrypted: Fix two crypto-on-the-stack bugs

[add some people who might know] On Tue, Dec 13, 2016 at 4:20 AM, David Laight wrote: > From: Andy Lutomirski >> Sent: 12 December 2016 20:53 >> The driver put a constant buffer of all zeros on the stack and >> pointed a scatterlist entry at it in two places. This

RE: [PATCH] keys/encrypted: Fix two crypto-on-the-stack bugs

From: Andy Lutomirski > Sent: 12 December 2016 20:53 > The driver put a constant buffer of all zeros on the stack and > pointed a scatterlist entry at it in two places. This doesn't work > with virtual stacks. Use a static 16-byte buffer of zeros instead. ... I didn't think you could dma from

Re: [PATCH] keys/encrypted: Fix two crypto-on-the-stack bugs

On Mon, Dec 12, 2016 at 2:28 PM, David Howells wrote: > Andy Lutomirski wrote: > >> +static const char zero_pad[16] = {0}; > > Isn't there a global page of zeros or something that we can share? Also, you > shouldn't explicitly initialise it so that it stays

Re: [PATCH] keys/encrypted: Fix two crypto-on-the-stack bugs

Andy Lutomirski wrote: > +static const char zero_pad[16] = {0}; Isn't there a global page of zeros or something that we can share? Also, you shouldn't explicitly initialise it so that it stays in .bss. > - sg_set_buf(_out[1], pad, sizeof pad); > + sg_set_buf(_out[1],