From 0227da01f2559626396af5f6c7453360db86c1f6 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Christian=20K=C3=B6nig?= Date: Fri, 9 Oct 2020 15:08:55 +0200 Subject: [PATCH] mm: mmap: fix fput in error path v2 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Jason Gunthorpe Link: https://patchwork.freedesktop.org/patch/394772/ --- 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 556f62e8b196..3d22dff1dab9 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);