misc: fastrpc: avoid double fput() on failed usercopy
If the copy back to userland fails for the FASTRPC_IOCTL_ALLOC_DMA_BUFF ioctl(), we shouldn't assume that 'buf->dmabuf' is still valid. In fact, dma_buf_fd() called fd_install() before, i.e. "consumed" one reference, leaving us with none. Calling dma_buf_put() will therefore put a reference we no longer own, leading to a valid file descritor table entry for an already released 'file' object which is a straight use-after-free. Simply avoid calling dma_buf_put() and rely on the process exit code to do the necessary cleanup, if needed, i.e. if the file descriptor is still valid. Fixes: 6cffd795 ("misc: fastrpc: Add support for dmabuf exporter") Acked-by:Christian König <christian.koenig@amd.com> Signed-off-by:
Mathias Krause <minipli@grsecurity.net> Link: https://lore.kernel.org/r/20220127130218.809261-1-minipli@grsecurity.net Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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26291c54
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