Patch "495c10cc1c0c CHROMIUM: dma-buf: restore args..." adds a workaround for a bug in mmap_region.

As the comment states ->mmap() callback can change vma->vm_file and so we might call fput() on the wrong file.

Revert the workaround and proper fix this in mmap_region.

v2: drop the extra if in dma_buf_mmap as well

Signed-off-by: Christian König christian.koenig@amd.com Reviewed-by: Jason Gunthorpe jgg@nvidia.com --- drivers/dma-buf/dma-buf.c | 20 +++----------------- mm/mmap.c | 2 +- 2 files changed, 4 insertions(+), 18 deletions(-)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 0eb80c1ecdab..282bd8b84170 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -1166,9 +1166,6 @@ EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access); int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma, unsigned long pgoff) { - struct file *oldfile; - int ret; - if (WARN_ON(!dmabuf || !vma)) return -EINVAL;

@@ -1186,22 +1183,11 @@ int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma, return -EINVAL;

/* readjust the vma */ - get_file(dmabuf->file); - oldfile = vma->vm_file; - vma->vm_file = dmabuf->file; + fput(vma->vm_file); + vma->vm_file = get_file(dmabuf->file); vma->vm_pgoff = pgoff;

- ret = dmabuf->ops->mmap(dmabuf, vma); - if (ret) { - /* restore old parameters on failure */ - vma->vm_file = oldfile; - fput(dmabuf->file); - } else { - if (oldfile) - fput(oldfile); - } - return ret; - + return dmabuf->ops->mmap(dmabuf, vma); } EXPORT_SYMBOL_GPL(dma_buf_mmap);

diff --git a/mm/mmap.c b/mm/mmap.c index d91ecb00d38c..30a4e8412a58 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1899,8 +1899,8 @@ unsigned long mmap_region(struct file *file, unsigned long addr, return addr;

unmap_and_free_vma: + fput(vma->vm_file); vma->vm_file = NULL; - fput(file);

/* Undo any partial mapping done by a device driver. */ unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);

Add the new vma_set_file() function to allow changing vma->vm_file with the necessary refcount dance.

v2: add more users of this. v3: add missing EXPORT_SYMBOL, rebase on mmap cleanup, add comments why we drop the reference on two occasions. v4: make it clear that changing an anonymous vma is illegal. v5: move vma_set_file to mm/util.c

Signed-off-by: Christian König christian.koenig@amd.com Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch (v2) Reviewed-by: Jason Gunthorpe jgg@nvidia.com --- drivers/dma-buf/dma-buf.c | 3 +-- drivers/gpu/drm/etnaviv/etnaviv_gem.c | 4 +--- drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 3 +-- drivers/gpu/drm/i915/gem/i915_gem_mman.c | 5 +++-- drivers/gpu/drm/msm/msm_gem.c | 4 +--- drivers/gpu/drm/omapdrm/omap_gem.c | 3 +-- drivers/gpu/drm/vgem/vgem_drv.c | 3 +-- drivers/staging/android/ashmem.c | 6 +++--- include/linux/mm.h | 2 ++ mm/util.c | 12 ++++++++++++ 10 files changed, 26 insertions(+), 19 deletions(-)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 282bd8b84170..e63684d4cd90 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -1183,8 +1183,7 @@ int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma, return -EINVAL;

/* readjust the vma */ - fput(vma->vm_file); - vma->vm_file = get_file(dmabuf->file); + vma_set_file(vma, dmabuf->file); vma->vm_pgoff = pgoff;

return dmabuf->ops->mmap(dmabuf, vma); diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/etnaviv/etnaviv_gem.c index 67d9a2b9ea6a..4132acfa11be 100644 --- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c +++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c @@ -145,10 +145,8 @@ static int etnaviv_gem_mmap_obj(struct etnaviv_gem_object *etnaviv_obj, * address_space (so unmap_mapping_range does what we want, * in particular in the case of mmap'd dmabufs) */ - fput(vma->vm_file); - get_file(etnaviv_obj->base.filp); vma->vm_pgoff = 0; - vma->vm_file = etnaviv_obj->base.filp; + vma_set_file(vma, etnaviv_obj->base.filp);

vma->vm_page_prot = vm_page_prot; } diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c index 0dd477e56573..04e9c04545ad 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c @@ -114,8 +114,7 @@ static int i915_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct * if (ret) return ret;

- fput(vma->vm_file); - vma->vm_file = get_file(obj->base.filp); + vma_set_file(vma, obj->base.filp);

return 0; } diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/i915_gem_mman.c index 3d69e51f3e4d..ec28a6cde49b 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c @@ -893,8 +893,9 @@ int i915_gem_mmap(struct file *filp, struct vm_area_struct *vma) * requires avoiding extraneous references to their filp, hence why * we prefer to use an anonymous file for their mmaps. */ - fput(vma->vm_file); - vma->vm_file = anon; + vma_set_file(vma, anon); + /* Drop the initial creation reference, the vma is now holding one. */ + fput(anon);

switch (mmo->mmap_type) { case I915_MMAP_TYPE_WC: diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c index 2e1bce7c0b19..311721ceee50 100644 --- a/drivers/gpu/drm/msm/msm_gem.c +++ b/drivers/gpu/drm/msm/msm_gem.c @@ -212,10 +212,8 @@ int msm_gem_mmap_obj(struct drm_gem_object *obj, * address_space (so unmap_mapping_range does what we want, * in particular in the case of mmap'd dmabufs) */ - fput(vma->vm_file); - get_file(obj->filp); vma->vm_pgoff = 0; - vma->vm_file = obj->filp; + vma_set_file(vma, obj->filp);

vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); } diff --git a/drivers/gpu/drm/omapdrm/omap_gem.c b/drivers/gpu/drm/omapdrm/omap_gem.c index d8e09792793a..f063f5a04fb0 100644 --- a/drivers/gpu/drm/omapdrm/omap_gem.c +++ b/drivers/gpu/drm/omapdrm/omap_gem.c @@ -564,9 +564,8 @@ int omap_gem_mmap_obj(struct drm_gem_object *obj, * address_space (so unmap_mapping_range does what we want, * in particular in the case of mmap'd dmabufs) */ - fput(vma->vm_file); vma->vm_pgoff = 0; - vma->vm_file = get_file(obj->filp); + vma_set_file(vma, obj->filp);

vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); } diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c index fa54a6d1403d..ea0eecae5153 100644 --- a/drivers/gpu/drm/vgem/vgem_drv.c +++ b/drivers/gpu/drm/vgem/vgem_drv.c @@ -397,8 +397,7 @@ static int vgem_prime_mmap(struct drm_gem_object *obj, if (ret) return ret;

- fput(vma->vm_file); - vma->vm_file = get_file(obj->filp); + vma_set_file(vma, obj->filp); vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP; vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));

diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c index 10b4be1f3e78..4789d36ddfd3 100644 --- a/drivers/staging/android/ashmem.c +++ b/drivers/staging/android/ashmem.c @@ -450,9 +450,9 @@ static int ashmem_mmap(struct file *file, struct vm_area_struct *vma) vma_set_anonymous(vma); }

- if (vma->vm_file) - fput(vma->vm_file); - vma->vm_file = asma->file; + vma_set_file(vma, asma->file); + /* XXX: merge this with the get_file() above if possible */ + fput(asma->file);

out: mutex_unlock(&ashmem_mutex); diff --git a/include/linux/mm.h b/include/linux/mm.h index ef360fe70aaf..2b7ac36c42dd 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2719,6 +2719,8 @@ static inline void vma_set_page_prot(struct vm_area_struct *vma) } #endif

+void vma_set_file(struct vm_area_struct *vma, struct file *file); + #ifdef CONFIG_NUMA_BALANCING unsigned long change_prot_numa(struct vm_area_struct *vma, unsigned long start, unsigned long end); diff --git a/mm/util.c b/mm/util.c index 4ddb6e186dd5..8c9b7d1e7c49 100644 --- a/mm/util.c +++ b/mm/util.c @@ -311,6 +311,18 @@ int vma_is_stack_for_current(struct vm_area_struct *vma) return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t)); }

+/* + * Change backing file, only valid to use during initial VMA setup. + */ +void vma_set_file(struct vm_area_struct *vma, struct file *file) +{ + /* Changing an anonymous vma with this is illegal */ + get_file(file); + swap(vma->vm_file, file); + fput(file); +} +EXPORT_SYMBOL(vma_set_file); + #ifndef STACK_RND_MASK #define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12)) /* 8MB of VA */ #endif