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authorJoonas Lahtinen <joonas.lahtinen@linux.intel.com>2019-02-07 10:54:53 +0200
committerJoonas Lahtinen <joonas.lahtinen@linux.intel.com>2019-02-07 14:10:35 +0200
commit5c4604e757ba9b193b09768d75a7d2105a5b883f (patch)
tree8d3109a412a8bb23a5b53be76d5ba079f296952f
parent6cbb55c086b4f23ad100f34cdeab496c4e99e0a6 (diff)
drm/i915: Prevent a race during I915_GEM_MMAP ioctl with WC set
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 <adamza@microsoft.com> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: <stable@vger.kernel.org> # v4.0+ Cc: Akash Goel <akash.goel@intel.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com> Cc: Adam Zabrocki <adamza@microsoft.com> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> #v1 Link: https://patchwork.freedesktop.org/patch/msgid/20190207085454.10598-1-joonas.lahtinen@linux.intel.com
-rw-r--r--drivers/gpu/drm/i915/i915_gem.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 52b5a24be42b..2ea9b423de49 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1679,6 +1679,16 @@ i915_gem_sw_finish_ioctl(struct drm_device *dev, void *data,
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.
@@ -1737,7 +1747,7 @@ i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
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