io_uring: fix not locked access to fixed buf table
commit 05b538c1 upstream. We can look inside the fixed buffer table only while holding ->uring_lock, however in some cases we don't do the right async prep for IORING_OP_{WRITE,READ}_FIXED ending up with NULL req->imu forcing making an io-wq worker to try to resolve the fixed buffer without proper locking. Move req->imu setup into early req init paths, i.e. io_prep_rw(), which is called unconditionally for rw requests and under uring_lock. Fixes: 634d00df ("io_uring: add full-fledged dynamic buffers support") Signed-off-by:Pavel Begunkov <asml.silence@gmail.com> Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
parent
5696f798
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