diff options
| author | Wachowski, Karol <karol.wachowski@intel.com> | 2024-05-20 12:05:14 +0200 |
|---|---|---|
| committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2024-05-21 14:38:51 +0200 |
| commit | 39bc27bd688066a63e56f7f64ad34fae03fbe3b8 (patch) | |
| tree | 257e12ec02a126d4da05fa344aed389d8e213546 | |
| parent | 520fb7f183e9b4d0ad7a2f084f3c4987845425e2 (diff) | |
drm/shmem-helper: Fix BUG_ON() on mmap(PROT_WRITE, MAP_PRIVATE)drm-misc-fixes-2024-05-23
Lack of check for copy-on-write (COW) mapping in drm_gem_shmem_mmap
allows users to call mmap with PROT_WRITE and MAP_PRIVATE flag
causing a kernel panic due to BUG_ON in vmf_insert_pfn_prot:
BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
Return -EINVAL early if COW mapping is detected.
This bug affects all drm drivers using default shmem helpers.
It can be reproduced by this simple example:
void *ptr = mmap(0, size, PROT_WRITE, MAP_PRIVATE, fd, mmap_offset);
ptr[0] = 0;
Fixes: 2194a63a818d ("drm: Add library for shmem backed GEM objects")
Cc: Noralf Trønnes <noralf@tronnes.org>
Cc: Eric Anholt <eric@anholt.net>
Cc: Rob Herring <robh@kernel.org>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: David Airlie <airlied@gmail.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: dri-devel@lists.freedesktop.org
Cc: <stable@vger.kernel.org> # v5.2+
Signed-off-by: Wachowski, Karol <karol.wachowski@intel.com>
Signed-off-by: Jacek Lawrynowicz <jacek.lawrynowicz@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20240520100514.925681-1-jacek.lawrynowicz@linux.intel.com
| -rw-r--r-- | drivers/gpu/drm/drm_gem_shmem_helper.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index e435f986cd13..1ff0678be7c7 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -610,6 +610,9 @@ int drm_gem_shmem_mmap(struct drm_gem_shmem_object *shmem, struct vm_area_struct return ret; } + if (is_cow_mapping(vma->vm_flags)) + return -EINVAL; + dma_resv_lock(shmem->base.resv, NULL); ret = drm_gem_shmem_get_pages(shmem); dma_resv_unlock(shmem->base.resv); |