CVE-2025-38595
Description
From CVE.org
In the Linux kernel, the following vulnerability has been resolved: xen: fix UAF in dmabuf_exp_from_pages() [dma_buf_fd() fixes; no preferences regarding the tree it goes through - up to xen folks] 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(). gntdev dmabuf_exp_from_pages() calls it and then proceeds to access the objects destroyed on close - starting with gntdev_dmabuf itself. Fix that by doing reserving descriptor before anything else and do fd_install() only when everything had been set up.
Statement
Red Hat Enterprise Linux is not impacted by this vulnerability because the Xen grant device DMA-buf export functionality is not enabled or present in supported Red Hat kernels. In upstream kernels, a concurrent thread closing an exported descriptor could cause an untimely release of resources, leading to a use-after-free condition. Because the required driver configuration is omitted from standard enterprise distributions, systems remain protected against exploitation.
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