From: Pavel Begunkov asml.silence@gmail.com
[ Upstream commit d11d31fc5d8a96f707facee0babdcffaafa38de2 ]
Fixed buffer table quiesce might unlock ->uring_lock, potentially letting new requests to be submitted, don't allow those requests to use the table as they will race with unregistration.
Reported-and-tested-by: van fantasy g1042620637@gmail.com Fixes: bd54b6fe3316ec ("io_uring: implement fixed buffers registration similar to fixed files") Signed-off-by: Pavel Begunkov asml.silence@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/io_uring.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/fs/io_uring.c b/fs/io_uring.c index 0a9f9000fc80..3d123ca028c9 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -9495,12 +9495,19 @@ static void __io_sqe_buffers_unregister(struct io_ring_ctx *ctx)
static int io_sqe_buffers_unregister(struct io_ring_ctx *ctx) { + unsigned nr = ctx->nr_user_bufs; int ret;
if (!ctx->buf_data) return -ENXIO;
+ /* + * Quiesce may unlock ->uring_lock, and while it's not held + * prevent new requests using the table. + */ + ctx->nr_user_bufs = 0; ret = io_rsrc_ref_quiesce(ctx->buf_data, ctx); + ctx->nr_user_bufs = nr; if (!ret) __io_sqe_buffers_unregister(ctx); return ret;