Re: [PATCH][next] nouveau/svm: Fix missing failure check on call to make_device_exclusive_range

On Thursday, 27 May 2021 12:04:59 AM AEST Colin King wrote:

The call to make_device_exclusive_range can potentially fail leaving pointer page not initialized that leads to an uninitialized pointer read issue. Fix this by adding a check to see if the call failed and returning the error code.

Addresses-Coverity: ("Uninitialized pointer read") Fixes: c620bba9828c ("nouveau/svm: implement atomic SVM access") Signed-off-by: Colin Ian King colin.king@canonical.com

---

drivers/gpu/drm/nouveau/nouveau_svm.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c b/drivers/gpu/drm/nouveau/nouveau_svm.c index 84726a89e665..b913b4907088 100644 --- a/drivers/gpu/drm/nouveau/nouveau_svm.c +++ b/drivers/gpu/drm/nouveau/nouveau_svm.c @@ -609,8 +609,10 @@ static int nouveau_atomic_range_fault(struct nouveau_svmm *svmm,

            notifier_seq = mmu_interval_read_begin(&notifier->notifier);

mmap_read_lock(mm);

•           make_device_exclusive_range(mm, start, start + PAGE_SIZE,
  

•                                       &page, drm->dev);
  

•           ret = make_device_exclusive_range(mm, start, start +
  

PAGE_SIZE, + &page, drm->dev); + if (ret < 0)

•                   goto out;
  

Thanks for spotting, this is fixing get_user_pages() inside make_device_exclusive_range() returning an error. However the check needs to happen after dropping mmap_lock below:

            mmap_read_unlock(mm);
            if (!page) {
                    ret = -EINVAL;

-- 2.31.1