High [CVE-2026-63910] fix UAF in dma_buf_fd tracepoint
This high-severity Red Hat Linux advisory covers CVE-2026-63910 affecting Red Hat Enterprise Linux 9, Red Hat package: kernel-rt.
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Summary
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. A flaw was found in the Linux kernel's dma-buf (Direct Memory Access buffer) subsystem.
A race condition in the `dma_buf_fd()` tracepoint can lead to a Use-After-Free (UAF) vulnerability. A local attacker could exploit this by closing a file descriptor (fd) prematurely, causing the `dma_buf` to be freed while the tracepoint still attempts to access it.
This could result in a system crash or potentially lead to privilege escalation or arbitrary code execution.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 6 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 6 days ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 6 days ago·verify at source
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