Messages in this thread | | | Subject | Re: [PATCH RESEND] hwrng: core - don't pass stack allocated buffer to rng->read() | From | Laszlo Ersek <> | Date | Fri, 21 Oct 2016 23:34:08 +0200 |
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On 10/21/16 23:04, Andy Lutomirski wrote: > On Fri, Oct 21, 2016 at 1:48 PM, Laszlo Ersek <lersek@redhat.com> wrote: >> The virtio-rng backend for hwrng passes the buffer that it receives for >> filling to sg_set_buf() directly, in: >> >> virtio_read() [drivers/char/hw_random/virtio-rng.c] >> register_buffer() [drivers/char/hw_random/virtio-rng.c] >> sg_init_one() [lib/scatterlist.c] >> sg_set_buf() [include/linux/scatterlist.h] >> >> In turn, the sg_set_buf() function, when built with CONFIG_DEBUG_SG, >> actively enforces (justifiedly) that the buffer used within the >> scatter-gather list live in physically contiguous memory: >> >> BUG_ON(!virt_addr_valid(buf)); >> >> The combination of the above two facts means that whatever calls >> virtio_read() -- via the hwrng.read() method -- has to allocate the >> recipient buffer in physically contiguous memory. > > Indeed. This bug should be fixed by: > > https://git.kernel.org/cgit/linux/kernel/git/herbert/cryptodev-2.6.git/commit/?id=6d4952d9d9d4dc2bb9c0255d95a09405a1e958f7 >
Cool, thanks!
(My commit message is better tho ;))
Cheers Laszlo
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