[pull] master from torvalds:master#1941
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pull[bot] merged 2 commits intozaixi:masterfrom Aug 13, 2025
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As soon as we'd inserted a file reference into descriptor table, another thread could close it. That's fine for the case when all we are doing is returning that descriptor to userland (it's a race, but it's a userland race and there's nothing the kernel can do about it). However, if we follow fd_install() with any kind of access to objects that would be destroyed on close (be it the struct file itself or anything destroyed by its ->release()), we have a UAF. dma_buf_fd() is a combination of reserving a descriptor and fd_install(). habanalabs export_dmabuf() calls it and then proceeds to access the objects destroyed on close. In particular, it grabs an extra reference to another struct file that will be dropped as part of ->release() for ours; that "will be" is actually "might have already been". Fix that by reserving descriptor before anything else and do fd_install() only when everything had been set up. As a side benefit, we no longer have the failure exit with file already created, but reference to underlying file (as well as ->dmabuf_export_cnt, etc.) not grabbed yet; unlike dma_buf_fd(), fd_install() can't fail. Fixes: db1a8dd ("habanalabs: add support for dma-buf exporter") Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
…it/viro/vfs Pull habanalabs fix from Al Viro: "Yet another use-after-free fix due to dma_buf_fd() misuse" * tag 'pull-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: habanalabs: fix UAF in export_dmabuf()
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