On Fri, Feb 2, 2024 at 4:56 PM David Hildenbrand <da...@redhat.com> wrote:
>
> We already use MADV_NORESERVE to deal with sparse memory regions. Let's
> also set madvise(MADV_DONTDUMP), otherwise a crash of the process can
> result in us allocating all memory in the mmap'ed region for dumping
> purposes.
>
> This change implies that the mmap'ed rings won't be included in a
> coredump. If ever required for debugging purposes, we could mark only
> the mapped rings MADV_DODUMP.
>
> Ignore errors during madvise() for now.
>
> Signed-off-by: David Hildenbrand <da...@redhat.com>
Reviewed-by: Raphael Norwitz <raph...@enfabrica.net>
> ---
> subprojects/libvhost-user/libvhost-user.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/subprojects/libvhost-user/libvhost-user.c
> b/subprojects/libvhost-user/libvhost-user.c
> index 738e84ab63..26c289518c 100644
> --- a/subprojects/libvhost-user/libvhost-user.c
> +++ b/subprojects/libvhost-user/libvhost-user.c
> @@ -458,6 +458,12 @@ _vu_add_mem_reg(VuDev *dev, VhostUserMemoryRegion
> *msg_region, int fd)
> DPRINT(" mmap_addr: 0x%016"PRIx64"\n",
> (uint64_t)(uintptr_t)mmap_addr);
>
> +#if defined(__linux__)
> + /* Don't include all guest memory in a coredump. */
> + madvise(mmap_addr, msg_region->memory_size + mmap_offset,
> + MADV_DONTDUMP);
> +#endif
> +
> /* Shift all affected entries by 1 to open a hole at idx. */
> r = &dev->regions[idx];
> memmove(r + 1, r, sizeof(VuDevRegion) * (dev->nregions - idx));
> --
> 2.43.0
>
>
