From: "Christian König" <ckoenig.leichtzumerken@gmail.com> To: akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linaro-mm-sig@lists.linaro.org, dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org Subject: [PATCH 1/2] mm: mmap: fix fput in error path v2 Date: Fri, 6 Nov 2020 12:48:05 +0100 [thread overview] Message-ID: <20201106114806.46015-2-christian.koenig@amd.com> (raw) In-Reply-To: <20201106114806.46015-1-christian.koenig@amd.com> 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); -- 2.25.1
WARNING: multiple messages have this Message-ID (diff)
From: "Christian König" <ckoenig.leichtzumerken@gmail.com> To: akpm@linux-foundation.org Cc: linaro-mm-sig@lists.linaro.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org Subject: [PATCH 1/2] mm: mmap: fix fput in error path v2 Date: Fri, 6 Nov 2020 12:48:05 +0100 [thread overview] Message-ID: <20201106114806.46015-2-christian.koenig@amd.com> (raw) In-Reply-To: <20201106114806.46015-1-christian.koenig@amd.com> 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); -- 2.25.1 _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
next prev parent reply other threads:[~2020-11-06 11:48 UTC|newest] Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-11-06 11:48 cleanup a fix and add the vma_set_file function Christian König 2020-11-06 11:48 ` Christian König 2020-11-06 11:48 ` Christian König [this message] 2020-11-06 11:48 ` [PATCH 1/2] mm: mmap: fix fput in error path v2 Christian König 2020-11-06 22:48 ` Andrew Morton 2020-11-06 22:48 ` Andrew Morton 2020-11-18 10:57 ` Christian König 2020-11-18 10:57 ` Christian König 2020-11-18 22:27 ` Andrew Morton 2020-11-18 22:27 ` Andrew Morton 2020-11-06 11:48 ` [PATCH 2/2] mm: introduce vma_set_file function v5 Christian König 2020-11-06 11:48 ` Christian König -- strict thread matches above, loose matches on Subject: below -- 2020-10-12 8:52 [PATCH 1/2] mm: mmap: fix fput in error path v2 Christian König 2020-10-12 8:52 ` Christian König 2020-10-16 16:13 ` Jason Gunthorpe 2020-10-16 16:13 ` Jason Gunthorpe 2020-11-04 8:03 ` Christian König 2020-11-04 8:03 ` Christian König
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