From: Rob Clark robdclark@chromium.org

mainline inclusion from mainline-v6.1 commit 24013314be6ee4ee456114a671e9fa3461323de8 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAYRIR CVE: CVE-2022-48981

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

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drm_gem_shmem_mmap() doesn't own this reference, resulting in the GEM object getting prematurely freed leading to a later use-after-free.

Link: https://syzkaller.appspot.com/bug?extid=c8ae65286134dd1b800d Reported-by: syzbot+c8ae65286134dd1b800d@syzkaller.appspotmail.com Fixes: 2194a63a818d ("drm: Add library for shmem backed GEM objects") Cc: stable@vger.kernel.org Signed-off-by: Rob Clark robdclark@chromium.org Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch Signed-off-by: Javier Martinez Canillas javierm@redhat.com Link: https://patchwork.freedesktop.org/patch/msgid/20221130185748.357410-2-robdcl... Signed-off-by: Qi Xi xiqi2@huawei.com --- drivers/gpu/drm/drm_gem_shmem_helper.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index 8d1abf82d2b9..2688009df321 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -621,10 +621,8 @@ int drm_gem_shmem_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma) shmem = to_drm_gem_shmem_obj(obj);

ret = drm_gem_shmem_get_pages(shmem); - if (ret) { - drm_gem_vm_close(vma); + if (ret) return ret; - }

vma->vm_flags |= VM_MIXEDMAP | VM_DONTEXPAND; vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);