[vbox-dev] [PATCH] additons/linux/drm: Fix NULL pointer dereference kernel oops on kernel 4.10+

[Frank Mehnert]

On Mittwoch, 31. Mai 2017 21:50:04 CEST Michael Thayer wrote:
> 17.05.2017 13:42, Hans de Goede wrote:
> > The vboxvideo causes a NULL pointer dereference inside the kernel on
> > kernel 4.10+ when ttm needs to make room in the video memory and tries
> > to evict things.
> > 
> > This is caused by upstream kernel commit a2ab19fed9d1 ("drm/ttm: make
> > eviction decision a driver callback v2") introducing a new
> > eviction_valuable callback which the vboxvideo driver does not define:
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit?id=a2ab19fed9d1dc5a7a2ced44f4b289885c522a8f
> > 
> > This commit adds a definition for this callback, fixing the crash.
> > 
> > Signed-off-by: Hans de Goede <hdegoede at redhat.com>
> [...]
> 
> Thanks Hans, committed!  Updated slightly for a similar problem with 
> 4.11 and later:
> 
> Index: src/VBox/Additions/linux/drm/vbox_ttm.c
> ===================================================================
> --- src/VBox/Additions/linux/drm/vbox_ttm.c	(revision 115843)
> +++ src/VBox/Additions/linux/drm/vbox_ttm.c	(working copy)
> @@ -262,11 +262,17 @@
>       .ttm_tt_populate = vbox_ttm_tt_populate,
>       .ttm_tt_unpopulate = vbox_ttm_tt_unpopulate,
>       .init_mem_type = vbox_bo_init_mem_type,
> +#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 10, 0)
> +    .eviction_valuable = ttm_bo_eviction_valuable,
> +#endif
>       .evict_flags = vbox_bo_evict_flags,
>       .move = vbox_bo_move,
>       .verify_access = vbox_bo_verify_access,
>       .io_mem_reserve = &vbox_ttm_io_mem_reserve,
>       .io_mem_free = &vbox_ttm_io_mem_free,
> +#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 11, 0)
> +    .io_mem_pfn = ttm_bo_default_io_mem_pfn,
> +#endif
>   #if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 7, 0) && 
> LINUX_VERSION_CODE < KERNEL_VERSION(4, 11, 0)
>       .lru_tail = &ttm_bo_default_lru_tail,
>       .swap_lru_tail = &ttm_bo_default_swap_lru_tail,
> 
> Regards
> Michael

actually ttm_bo_default_io_mem_pfn() is available as of Linux 4.12, not 4.11!
Fixed that.

Frank
-- 
Dr.-Ing. Frank Mehnert | Software Development Director, VirtualBox
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