CVE-2025-38722

In the Linux kernel, the following vulnerability has been resolved:

habanalabs: fix UAF in export_dmabuf()

As soon as wed inserted a file reference into descriptor table, another thread could close it. Thats fine for the case when all we are doing is returning that descriptor to userland (its a race, but its a userland race and theres 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() cant fail.

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/33927f3d0ecdcff06326d6e4edb6166aed42811c
• https://git.kernel.org/stable/c/40deceb38f9db759772d1c289c28fd2a543f57fc
• https://git.kernel.org/stable/c/55c232d7e0241f1d5120b595e7a9de24c75ed3d8
• https://git.kernel.org/stable/c/c07886761fd6251db6938d4e747002e3d150d231