CVE-2026-63910

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

dma-buf: fix UAF in dma_buf_fd() tracepoint

Once FD_ADD() returns, the fd is live in the file descriptor table and a thread sharing that table can close() it before DMA_BUF_TRACE() runs. The close drops the last reference, __fput() frees the dma_buf, and the tracepoint then dereferences dmabuf to take dmabuf->name_lock – slab-use-after-free.

Split FD_ADD() back into get_unused_fd_flags() + fd_install() and emit the tracepoint between them. While the fdtable slot is reserved with a NULL file pointer, a racing close() returns -EBADF without entering __fput(), so the dma_buf stays alive across the trace. Same approach as commit 2d76319c4cbb (dma-buf: fix UAF in dma_buf_put() tracepoint).

This undoes the FD_ADD() conversion done in commit 34dfce523c90 (dma: convert dma_buf_fd() to FD_ADD()); FD_ADD() has no place to hook the tracepoint safely.

Affected Software

References

• https://git.kernel.org/stable/c/b569f86e2f8dbf6f11d31d3de794d22e18098b23
• https://git.kernel.org/stable/c/ead6680f354f83966c796fc7f9463a3171789616