linux/io_uring/kbuf.h
Jens Axboe 7138ebbe65 io_uring/kbuf: defer release of mapped buffer rings
commit c392cbecd8 upstream.

If a provided buffer ring is setup with IOU_PBUF_RING_MMAP, then the
kernel allocates the memory for it and the application is expected to
mmap(2) this memory. However, io_uring uses remap_pfn_range() for this
operation, so we cannot rely on normal munmap/release on freeing them
for us.

Stash an io_buf_free entry away for each of these, if any, and provide
a helper to free them post ->release().

Cc: stable@vger.kernel.org
Fixes: c56e022c0a ("io_uring: add support for user mapped provided buffer ring")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-12-08 08:52:20 +01:00

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3.9 KiB