Commit 2d76319c authored by Andi Shyti's avatar Andi Shyti Committed by Christian König
Browse files

dma-buf: fix UAF in dma_buf_put() tracepoint 



dma_buf_put() may drop the final file reference via fput(), which
can free the dma-buf. The new tracepoint invocation was added
after fput(), and DMA_BUF_TRACE() dereferences dmabuf and takes
dmabuf->name_lock.

This leads to a use-after-free on the final put, visible for
example as a spinlock bad magic fault on a poisoned 0x6b6b6b...
lock.

Move the dma_buf_put tracepoint before fput().

Reported-by: default avatarJanusz Krzysztofik <janusz.krzysztofik@linux.intel.com>
Fixes: 281a2263 ("dma-buf: add some tracepoints to debug.")
Signed-off-by: default avatarAndi Shyti <andi.shyti@linux.intel.com>
Reviewed-by: default avatarChristian König <christian.koenig@amd.com>
Signed-off-by: default avatarChristian König <christian.koenig@amd.com>
Link: https://lore.kernel.org/r/20260408123916.2604101-1-andi.shyti@kernel.org
parent eecdd4bd

drivers/dma-buf/dma-buf.c

+1 −2
Original line number Diff line number Diff line
@@ -845,9 +845,8 @@ void dma_buf_put(struct dma_buf *dmabuf) 
	if (WARN_ON(!dmabuf || !dmabuf->file))

		return;



	fput(dmabuf->file);



	DMA_BUF_TRACE(trace_dma_buf_put, dmabuf);

	fput(dmabuf->file);

}

EXPORT_SYMBOL_NS_GPL(dma_buf_put, "DMA_BUF");