4.20-stable review patch. If anyone has any objections, please let me know.
------------------ From: Joonas Lahtinen <[email protected]> commit 2e7bd10e05afb866b5fb13eda25095c35d7a27cc upstream. Make sure the underlying VMA in the process address space is the same as it was during vm_mmap to avoid applying WC to wrong VMA. A more long-term solution would be to have vm_mmap_locked variant in linux/mmap.h for when caller wants to hold mmap_sem for an extended duration. v2: - Refactor the compare function Fixes: 1816f9236303 ("drm/i915: Support creation of unbound wc user mappings for objects") Reported-by: Adam Zabrocki <[email protected]> Suggested-by: Linus Torvalds <[email protected]> Signed-off-by: Joonas Lahtinen <[email protected]> Cc: <[email protected]> # v4.0+ Cc: Akash Goel <[email protected]> Cc: Chris Wilson <[email protected]> Cc: Tvrtko Ursulin <[email protected]> Cc: Adam Zabrocki <[email protected]> Reviewed-by: Chris Wilson <[email protected]> Reviewed-by: Tvrtko Ursulin <[email protected]> #v1 Link: https://patchwork.freedesktop.org/patch/msgid/[email protected] (cherry picked from commit 5c4604e757ba9b193b09768d75a7d2105a5b883f) Signed-off-by: Jani Nikula <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- drivers/gpu/drm/i915/i915_gem.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -1826,6 +1826,16 @@ i915_gem_sw_finish_ioctl(struct drm_devi return 0; } +static inline bool +__vma_matches(struct vm_area_struct *vma, struct file *filp, + unsigned long addr, unsigned long size) +{ + if (vma->vm_file != filp) + return false; + + return vma->vm_start == addr && (vma->vm_end - vma->vm_start) == size; +} + /** * i915_gem_mmap_ioctl - Maps the contents of an object, returning the address * it is mapped to. @@ -1884,7 +1894,7 @@ i915_gem_mmap_ioctl(struct drm_device *d return -EINTR; } vma = find_vma(mm, addr); - if (vma) + if (vma && __vma_matches(vma, obj->base.filp, addr, args->size)) vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags)); else
