From 15325e3c1013035c2e3e266ba79a0c3bef905f25 Mon Sep 17 00:00:00 2001 From: Christian König Date: Thu, 11 Nov 2021 15:18:34 +0100 Subject: dma-buf: drop the DAG approach for the dma_resv object v3 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit So far we had the approach of using a directed acyclic graph with the dma_resv obj. This turned out to have many downsides, especially it means that every single driver and user of this interface needs to be aware of this restriction when adding fences. If the rules for the DAG are not followed then we end up with potential hard to debug memory corruption, information leaks or even elephant big security holes because we allow userspace to access freed up memory. Since we already took a step back from that by always looking at all fences we now go a step further and stop dropping the shared fences when a new exclusive one is added. v2: Drop some now superflous documentation v3: Add some more documentation for the new handling. Signed-off-by: Christian König Reviewed-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20220321135856.1331-11-christian.koenig@amd.com --- include/linux/dma-buf.h | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) (limited to 'include/linux/dma-buf.h') diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index 7ab50076e7a6..85ab5554425e 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -424,9 +424,7 @@ struct dma_buf { * IMPORTANT: * * All drivers must obey the struct dma_resv rules, specifically the - * rules for updating fences, see &dma_resv.fence_excl and - * &dma_resv.fence. If these dependency rules are broken access tracking - * can be lost resulting in use after free issues. + * rules for updating and obeying fences. */ struct dma_resv *resv; -- cgit