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Mikhail GavrilovandGreg Kroah-Hartman
f3df4a783b
commitfb7b1a0ab2upstream. begin_cpu_udmabuf() maps the sg_table with the caller-provided direction (e.g., DMA_TO_DEVICE for a write-only sync), and caches it in ubuf->sg for reuse. However, release_udmabuf() always unmaps this sg_table with a hardcoded DMA_BIDIRECTIONAL, regardless of the direction that was originally used for the mapping. With CONFIG_DMA_API_DEBUG=y this produces: DMA-API: misc udmabuf: device driver frees DMA memory with different direction [device address=0x000000044a123000] [size=4096 bytes] [mapped with DMA_TO_DEVICE] [unmapped with DMA_BIDIRECTIONAL] The issue was found during video playback when GStreamer performed a write-only DMA_BUF_IOCTL_SYNC on a udmabuf. It can be reproduced with CONFIG_DMA_API_DEBUG=y by creating a udmabuf from a memfd, performing a write-only sync (DMA_BUF_SYNC_WRITE without DMA_BUF_SYNC_READ), and closing the file descriptor. Fix this by storing the DMA direction used when the sg_table is first created in begin_cpu_udmabuf(), and passing that same direction to put_sg_table() in release_udmabuf(). Fixes:284562e1f3("udmabuf: implement begin_cpu_access/end_cpu_access hooks") Cc: stable@vger.kernel.org Signed-off-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com> Reviewed-by: Vivek Kasireddy <vivek.kasireddy@intel.com> Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com> Link: https://patch.msgid.link/20260314232722.15555-1-mikhail.v.gavrilov@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>